Disease in Captive Wild Mammals and Birds

FOREWORD — SECTION I INTRODUCTION

The work on which this book is based was begun in November, 1901. From that date, systematic autopsies were made on animals dying in the Philadelphia Zoological Garden. Previously autopsies had been made very rarely and only on animals of especial importance and interest. Pathological conditions were occasionally noted in animals subjected to anatomical study. The work was strictly volunteer, for there was no one on whom the Society had the right to call. Dr. Henry C. Chapman, a former Director, whose interest was in physiology and comparative anatomy, made nearly all the autopsies that were made before the beginning of the present work. In the annual reports from the foundation of the Garden in 1872, very few such examinations are recorded. In some reports there are lists of important deaths, but no record of the cause of death.

This state of things was not peculiar to the Philadelphia Garden. It existed in every zoological garden in the world. It exists in most of them to-day. When an animal died it had no interest or value except for its hide and bones. Rare specimens were sent to the Academy of Natural Sciences from the Philadelphia Garden. The great majority, however, were immediately destroyed, and thus during the twenty-nine years from the foundation of the Garden, preceding this work, there have been lost many opportunities—some of which will never recur—of increasing our knowledge of pathology.

This book gives results of the study of animals that have not been subjected to experimental procedures and conditions, and though their mode of life has not been 2that strictly natural to them, yet they have not been influenced by any of the artificial procedures of the laboratory which are usually followed in investigations on animals. Though the object of the work was the pursuit of knowledge for its own sake, yet results of practical value have followed: hygiene has been improved; disinfection has been made scientific; epidemics have been arrested; some diseases, notably tuberculosis in monkeys, and spiropteriasis in parrots, have been practically eliminated.

The value of the work is recognized by the keepers. Their interest has increased and their morale has improved. The frequent deaths in a large collection of animals are discouraging, and a good animal man must have courage and optimism—traits that are stimulated by the knowledge that every animal that dies is studied to determine the cause of death, and to prevent its recurrence.

Some results of this study are to be considered as “raw material,” while others permit cautious or tentative conclusions. The first include—visceral weights, incidence of certain lesions like anemia and hepatic cirrhoses, occurrence of calculi and observations on weak hind quarters, convulsions and constitutional diseases. The second include—eradication of tuberculosis and spiropteriasis, the response of the mammalian and avian heart to strain and disease viruses, the origin of pneumonia in birds, the genesis of bronchiectasis, the nature of osseous degeneration with relation to diet and alimentary tract, the comparative anatomy, physiology and pathology of the female genitalia, the occurrence of lesions in the thyroid comparable to those in man, the character of kangaroo disease.

Great praise is due Dr. Herbert Fox and his assistants Drs. F. D. Weidman and E. P. Corson-White, for the splendid scientific spirit and thoroughness with which they have done this work, with no adequate remuneration, 3except the intangible reward appreciated only by the real research worker.

It is a mistake to think that all animals in the wild state are healthy. The healthy wild animals that we see are the survivors, the sick and the weaklings having died. Undoubtedly diseases are fewer than in captive animals; but on the other hand wild animals are exposed to dangers to which captive animals are not exposed—such as lack of care in sickness and old age, starvation, and attacks of enemies that feed on them. The maximum longevities in some species are probably in captive animals. It is doubtful if a wild animal ever reaches the greatest age possible to it.

Many kinds of parasites have been found in wild animals captured only a short time before arriving at the Garden, so that they must have existed in the wild. Thirteen wild cats received from South Carolina within a few days after capture were infested with intestinal, muscular, and pulmonary parasites. Several years ago there were received from the Island of Chincoteague, off the coast of Virginia, a number of native birds recently captured, all of which had mould disease of the air sacs. This happened on several occasions, so that it became necessary to reject all birds from this locality. Among the birds were meadow larks and cardinals.

Hunters not infrequently kill animals with disease, and if more hunters knew enough to recognize the disease there would be more recorded cases. Sick animals are not as likely to be killed by the hunter as healthy ones, as sick animals seek seclusion and do not move about. In many localities of the United States white-tailed deer are infested with the liver-fluke. Trout and other fish in remote mountain streams are found with tapeworms. Round worms and other parasites infest the white rhinoceros in the African forest.

4In many instances the parasites and the host, when in health, get on very well together; but when the host weakens the parasites may give him the finishing stroke.

Though some morbid conditions described in this book are peculiar to captivity, yet it seems reasonable to assume that many of the diseases found in captive animals occur also in the wild. Some of the extinct races of animals may have been wiped out by disease.

Captivity causes numerous physical and mental disarrangements. Unaccustomed, unnatural and unvaried food, change of climate and environment, physical and mental degeneration from disuse of muscle and brain, fear, ennui, nostalgia, lack of the exhilaration of chasing and being chased, unsatisfied sexual feeling—all react harmfully on the captive.

No captive animals get their natural food; and though some, like the carnivora, may get approximately their natural food, yet they do not get it in the natural way. They have but little variety and may miss elements important to their well-being. They get only certain cuts—muscle and bone; they do not get blood, guts and glands. The lion’s meat is handed to him. He does not tear down his prey; and one result is that the jaws of the captive-bred lion differ decidedly in shape from the jaws of the wild-bred lion. He gets his food regularly, with awful monotony—twelve pounds of meat at 3.30 p.m. day after day; there is no alternation of feasts and fasts, with consequent change in the balance of the body reserves.

Some animals, such as caribou, the moose, the black cock, the hoatzin, the koala, do not long survive captivity, because it is impracticable to obtain their natural food. Gastrointestinal disease is the commonest disease of wild animals. Twenty-five per cent. of sick humans in civilized communities also suffer from it. On the other hand, many animals become accustomed to the new diet and thrive on it.

5Animals also often thrive in a climate very different from that of their natural habitat. Some animals from warm countries, though kept outside without any artificial heat, get on very well during the severe weather of Philadelphia winters, when the temperature often drops to zero Fahrenheit. For the past two years it has been the custom to put outdoors all monkeys—of value—that are suspected of having tuberculosis. The cheap monkeys are killed. The outdoor monkeys are kept in fair sized cages—five feet square and six feet high—usually singly, though sometimes two are together. The vervet, the grivet, the leonine macaque, the yellow baboon, the Hainan gibbon and many others, have not only survived the climatic conditions but have not succumbed to tuberculosis. South American monkeys do not stand cold as well as Old World monkeys, and cannot be kept out in severe winter weather.

The monkeys that are kept indoors during winter have free access to the outside through swinging doors and they often go out voluntarily in the coldest weather. The same is true of other animals. A note made several years ago (February 12, 1914) states: “Temperature last night was 1° F. At 2 P.M. outside temperature 13° F., in carnivora house 25° F., elephant house 38° F., giraffe house 39° F., monkey house 42° F. Two Bengal tigers were voluntarily outside. Monkeys that have been out all winter are: two Barbary apes, Hainan gibbon, lion-tailed macaque, yellow baboon, grivet monkey, pigtailed macaque, and eleven rhesus macaques. All the animals appeared comfortable.”

The physical condition of the animal and the kind of cold—damp or dry—have much to do with its ability to stand low temperatures. Monkeys have passed through very severe winters without damage, and subsequently in a less severe winter have had frozen fingers, toes or tail.

The size of the cage or pen has not as much effect upon the well-being of the animal as might be expected. Reptiles, birds and mammals do as well in cages and pens of 6medium size as in very large ones. A deer or antelope in a large enclosure does not use all its domain. It usually has a favorite corner near the food, water and shelter, and stays there. Nor has a large enclosure been found perceptibly to diminish mortality from cage-mates. The stronger will follow the weaker until he gets him, no matter what the enclosure. Even in the large flying cage for birds it is necessary to keep out those of a scrappy disposition. From the point of view of the public small enclosures are more satisfactory.

Mental disease in captive animals offers a fascinating field for study—now chiefly speculative. Many conditions are present to produce it—all the conditions that cause prison psychoses in man. And many if not all the insane and perverted acts of animals have their counterpart in the human. Masturbation is very common in mammals. Eating of their own feces, coprophagy, is not infrequent, and is especially notable in one of the highest types—the Chimpanzee. Perhaps occasionally coprophagy may be due to some defect in diet. There is no instinctive disgust at excrement in the lower animals any more than there is in the uneducated child. Nevertheless, eating feces cannot be healthful, and probably does not occur in nature; and occurs only in the human with mental disease.

Some of the insane acts of animals if prevalent in the wild would probably cause the extinction of the race. Such are killing of the young by the father and by the mother; killing of the female by the male, usually during rutting time, in some instances reminding one of Sadism in man. This kind of sexual killing does not often occur in the wild. The female has a better chance to escape, and the male probably does not feel so inclined to damage her when he chooses her himself as when she is chosen for him by his gaoler. When the mother devours her young it is usually shortly after birth. I have, however, the record of a Jungle cat (Felis chaus) who ate two of her 7kittens when they were seven weeks old. Some of the domestic animals devour their young; the sow often does it, and occasionally the bitch.

Sucking, gnawing and eating parts of itself or of a cage-mate is not uncommon in a variety of animals. Bears lick their paws until they are sore; a monkey may gradually gnaw away its tail from the tip to the body; an ocelot (Felis chibigonazon) bit open his scrotum and devoured his testicle; a Tasmanian devil (Sarcophilus ursinus) bit off one of his front feet at the wrist; a monkey may gradually gnaw away its fingers; and numerous other self-inflicted mutilations occur. Often there is a local irritating cause, as skin disease, lice, or freezing. But in many cases no local cause can be found, as no local cause can be found for thumb-sucking or nail-biting in the human.

The surgery done by monkeys on their frozen fingers and toes is interesting. After the flesh has sloughed the monkey bites off the protruding phalanges, apparently without pain, so that satisfactory well-covered stumps are made.

Animals often mutilate their cage-mates in an amicable way as distinguished from fighting. A bear may lick its mate’s ears until the hair and skin are gone. A monkey may eat its mate’s tail or patches of its skin, the victim lying placidly while the process goes on. Many animals are addicted to perverted acts on their own or their mate’s sexual organs.

It is probable that the phenomena just mentioned are due to confinement, idleness and ennui, and that they do not often happen in nature where an animal is kept busy seeking his food, fighting and avoiding his enemies, attending to his mate or mates, and meeting the various vicissitudes of his environment.

It should be remembered, however, that the members of a wild species vary in intelligence and temperament, as humans do. There are morons and perverts among 8animals in the wild; but not being coddled by the normal members of the species, they have a poorer chance than has the subnormal human of surviving and of transmitting their peculiarities.

Fear, ennui, loneliness and nostalgia, by affecting the minds of captive animals, react on their physical condition. Some animals have the fear of man bred in them. The young often show it from time of birth. This is especially common in animals that have survived for generations in proximity to man. It is one reason for their survival. The mother and father may have become tame and gentle in captivity and yet the young one may be a wild thing from birth. Such fear is sometimes uncontrollable, an apparently slight cause making the animal dash itself against the fence of the enclosure. It is not mere speculation to discuss the physical effects of the emotions on the animal body. It has been shown that fear, anger, and grief bring about distinct measurable physical changes. Dr. Corson-White has found that the red corpuscles are increased by over two million per cubic centimetre in the blood of a cat frightened by a dog barking at it. The amount of blood sugar is also increased.

Such observations are suggestive in a consideration of the changes that may occur in a captive animal subjected to acute and chronic fear.

The monotony of a captive animal’s life is broken only by feeding, the sight and sounds of others in the same building or nearby, and by visitors. Many animals show their appreciation and pleasure when visitors approach, and some of the more intelligent animals, bears and monkeys and some birds, “show off” apparently to keep the visitors there. When there is nothing doing, some stand swaying their heads, like a weaving horse, or pacing the cage, inanely tagging at each turn the side of the cage with the head or other part of the body—often so persistently that a sore is produced. Nearly all animals are social and suffer from loneliness when kept by themselves. 9This is true even of the lowly forms. The keeper of the reptile house reported that a giant tortoise became despondent and refused to eat when his companion, a leopard tortoise, was taken from him, and that he braced up as soon as the leopard tortoise was returned. It is not necessary that the companion be of the same species, or even of the same family. A lion or a tiger may be satisfied with a little dog for a companion, and there was an African rhinoceros at the Philadelphia Garden that was very discontented and unhappy when alone and became perfectly satisfied when she was given a domestic goat as a cage-mate; and the huge rhinoceros stood for a good deal of butting and bullying from the goat without retaliating. A sympathetic keeper may do much to relieve the loneliness of the animals in his care.

Nostalgia, or homesickness, has been felt by all men. Some have died of it. The tradition among writers is that it affects young people and those who have been living nearest to a state of nature. In this country the American Indian and the negro are affected more than the whites. Much was written of it after the Franco-Prussian War and the American Civil War. It is a real condition, capable in extreme cases of causing death and of so weakening the sufferer as to make him more susceptible to the invasion of other diseases. At the present day we hear less of it among civilized people than formerly, perhaps because the conception of home has been broadened by modern methods of intercommunication. The wild animal’s conception of home is narrow; he comes directly from it into an environment where he may see many other animals, but not one of his own kind. Predisposing causes of nostalgia are stronger with him than with the human. That home means a great deal to animals is shown by the migration of birds—the return of the carrier pigeon, and of the lost dog, and of the swallow, which returns every year to the same nesting place.

10All animals long for the things of nature—open air, earth, grass and water. They are thrilled when their feet touch the sod. Even the hippopotamus gambols when he leaves his concrete house and his feet touch earth and grass.

The face and carriage of many animals cannot express feelings as in the human, though it is not unreasonable to assume that animals may indicate feelings by expression understood by their mates, though not understood or even noticed by man. When they can express it in a human way their feelings may be read. The dejection of nostalgia is especially shown by anthropoid apes. Gorillas have been noted for it from the earliest writers. The orang is prone to it, shows it by his attitude and expression, and sometimes dies of it.

It is stated in A Handbook of the Management of Animals in Captivity in Lower Bengal, p. 130, that elephants have been observed to shed tears abundantly if forced to leave their old home and surroundings. How much other animals who cannot express homesickness may feel it, and how often it is a cause of unhappiness, depression and predisposition to disease, it is impossible to say.

Most wild animals in captivity are sterile. The reason is not known. It shows the profound effect of captivity. It would be difficult to determine whether the sterility of a mating is the fault of the male or the female.

There is no apparent rule for sterility. Some families are always sterile in captivity, others are fertile, even with very unfavorable surroundings. The deer, horses, hippopotamuses, pigs, goats, sheep and oxen, are good breeders; while antelopes, rhinoceroses, giraffes, elephants, are poor breeders. Some members of a family may be good, others poor. The lion and puma breed fairly well; the tiger, leopard and jaguar, very poorly. Bears breed well, but the mother usually destroys her young.

11We cannot mate wild animals and birds simply by putting males and females together in the same cage. Domestic mammals and birds usually mate under such conditions, but wild ones often refuse. Many mammals and probably all birds that are not polyandrous or polygamous reserve the right to select their mates, and if the sexes are put together by man they may view each other with indifference or with animosity. There are many males and females of the same species of mammals at the Zoological Garden that will not consent to live together. A male monkey in a cage with several females will very often select one female for his mate and will have nothing to do with the others.

Among monkeys fertility varies greatly. It is not practical to determine the ratio among the various kinds, as some kinds are much commoner in zoological collections than others. I think that in general the Old World monkeys (Cercopithecidæ) are better breeders in captivity than those of the New World (Cebidæ). The anthropoid apes are very poor breeders indeed; of the many gibbons, orangs, and chimpanzees, that for years have been captive in Europe and America, it is probable that only the chimpanzee has bred, and that very rarely.

Refusal to mate, sterility, infanticide by father and mother, and sexual killing keep down reproduction in zoological gardens; and the number of young ones is a good indication of the character of a garden and of the provisions made for the happiness, comfort and health of the animals.

With the birds in a zoological garden the conditions for nesting and laying are not good. Caged birds have no material for a nest, no privacy and rarely lay an egg. The outdoor water birds and the outdoor upland birds with natural surroundings, with secluded retreats, lay and hatch very well. Birds like mammals apparently are indifferent to publicity when copulating, but seek 12seclusion for laying and nesting—from maternal fear for the safety of the young.

The sexual instinct in indoor caged birds in a zoological garden is dormant. Very few copulate and very few lay eggs; pigeons and Mexican conures (Conurus holochlorus) are exceptions to this general rule.

Probably because the sexual instinct is dormant the males never fight over the females among perching birds, and very rarely kill each other. In some species of finches, however, as the chestnut-eared (gn. Amadina), the females fight among themselves if there are not enough males.

Ovoviviparous reptiles breed more often in captivity than one would expect; and egg-laying snakes often lay eggs, which of course are only hatched artificially.

Birds suffer less than mammals from the psychological effect of captivity. The mental development of a bird is much lower. With few exceptions, like the ruffed grouse, the bird accepts captivity easily and becomes tame, though he will not stand being touched. He views his keeper and visitors with indifference or friendliness. If a bird house is bright, cheerful and sunny, all the inmates thrive and appear to be happy. These conditions undoubtedly affect the health of the bird, as is evidenced by their plumage; bright colors that are lost in a dark and gloomy house are retained and developed when the house is cheerful and sunny. There are some birds, however, that never retain their colors in the captivity of a zoological garden. Among them are the scarlet ibis, the American flamingo, and the roseate spoonbill. It has been suggested that the loss of color is due to the lack of something in the diet, mineral or organic, that the bird gets in its natural habitat. Tame scarlet ibises living with the chickens about the dwellings of natives in Venezuela retain their brilliant color. The material of the beautiful red color on the under surface of the wings of the touracou contains copper, yet these 13birds retain this color very well in captivity, even after several moultings.

The source of the copper has long been uncertain. In nature the birds are fruiteaters, and their diet in captivity consists of bone meal, zweibach, corn meal, white potatoes, eggs and carrots—foods that are usually assumed to contain no copper; and no copper utensils are used in the preparation of the food. Dr. John Marshall, however, writes me that all the common cereals contain minute quantities of copper; and Dr. Leon A. Ryan, University of Pennsylvania Medical Bulletin, June, 1907, states that copper may be found in animal tissues. Dr. E. P. Corson-White has found traces of copper in the bone meal used at the Philadelphia Zoological Garden. The copper in the red color of the touracou’s wing therefore comes from the food.

It is probable that a bright and cheerful bird house does not influence the color of birds by the direct action of light on the color as much as indirectly by improving the health and spirits of the birds. Coloration in birds is a very complicated proposition. It depends upon age, sex, season, health, light, heat, moisture, mode of life, and food. No one bird house can combine all the conditions necessary for the retention of natural colors in every species. The desert species from a habitat of intense light and dryness require for their color a different environment from the forest species, from a habitat of shade and moisture. The suppression of sexual feeling in captive birds may influence color. In nature the finest colors are attained by mating birds.

It may be said that all animals—except those of nocturnal habit—have a feeling of joy and well-being in fine weather and bright surroundings that reacts favorably on the general health.

The variability of the breeding period induced by captivity in many animals may be mentioned with sterility. It was shown some years ago in the Philadelphia 14Garden by the European brown bear which in one year gave birth on January 16th, and in the following year on July 25th. It is another evidence of the profound effect of captivity on the captive animal. I know of no observations of the effect of captivity on the period of gestation.

There is considerable mortality among captive animals from killing of cage-mates. I do not refer to sexual killing, already mentioned, or to fights over a female. Often males, with no females near, cannot be kept together; probably sexual jealousy is at the bottom of it. Antelope and deer are especially inclined to scrap. Even a large enclosure will not save the weaker male; the stronger follows him with horrible persistency, sometimes for days, around and around the enclosure, often at a walk, but always on the offensive, at least during the day; until, careless from weariness, the weaker is caught unawares and finished by a horn-thrust in the side.

Both birds and mammals often kill their mates when the mate is sick, or “down” from injury or disease. All animals hate sickness and death, and show their dislike by attacking or shunning it. Birds may get on happily together for months until one becomes sick, and as he crouches in a corner with ruffled feathers the others pick on him and finish him. The same is true of mammals, the sick one being horned or tramped to death by the mate with whom he had formerly been on most friendly terms. The keeper often reports an animal “killed by its mate,” whereas the mate has only given the coup de grace.

This brutality is not universal. Rarely a parrakeet will stand guard over his sick and dying mate; and we have seen a ratel—of a ferocious family—stand guard over and resist the removal of his sick companion.

The diagnosis of disease in wild animals is unsatisfactory; usually impossible; clinical study as we know it in the human is impossible. We know that the animal is sick, but not why. A certain group of symptoms accompanies 15all diseases—dull, rough coat or feathers, refusal to eat, weakness in the hind quarters, and finally getting down. They rarely show symptoms of pain—or at least we cannot read the symptoms. The pain of acute pancreatitis in man is violent, yet many animals die with it and we cannot tell that they suffer. Animals do not suffer as much as the human, and they stand the ravages of disease better than the human. At autopsy we often wonder how the animal could have lived with the conditions that are found. A monkey may be apparently well until a few days before his death, though his lungs and abdominal organs may be a mass of tubercle. A small red howler monkey (Alonata seniculus) was in apparent good health, playful and lively until twenty-four hours before his death from acute pancreatitis, though his stomach and intestines contained fifty-one nematode worms, some of which were eight inches in length.

As diagnosis is unsatisfactory, so is treatment. Usually all we can do is to treat symptoms; and by the time disease has advanced to the point of becoming externally noticeable, it has usually gone beyond the reach of medical treatment. It must also be remembered that drugs vary very much in their action in different families of animals. Nux vomica will not kill the gallinaceous birds of North America, and Tenant says that in Ceylon the hornbill feeds on the fruit of strychnos nux vomica. The pigeon is immune to opium. The Felidæ are said to be unusually susceptible to carbolic acid; veratrum viride is harmless to sheep and elk, but poisonous to the horse; dogs can take with impunity large quantities of cyanide of potassium. These statements are true when the drugs are administered by mouth—the usual way of giving them to wild animals. The action may be different if the drugs are administered intravenously or subcutaneously. Variations in effect when they are administered by mouth are often due to chemical variations in the digestive secretions. It is probable that the action of cyanide of potash 16on dogs depends on the amount of hydrochloric acid in the digestive tract.

When worms or their eggs are found in the stools vermifuges are used, and with some animals especially liable to infestation by intestinal worms, periodic doses of vermifuges are given as a prophylactic. Turpentine is given to the zebra at fixed intervals for the round worm; santonin, male fern and areca nut to the carnivora for the various worms that are so common in the intestinal tracts of these animals.

The work of the Laboratory of Pathology is throwing light on the subject of diagnosis, and though from the character of the clinical material diagnosis can never be as satisfactory as in the human, yet we may fairly hope for improvement. Prophylaxis is our chief reliance, and always will be.

“We have also parks and enclosures of all sorts, of beasts and birds; which we use not only for view and rareness, but likewise for dissections and trials, that thereby we may take light what may be wrought upon the body of man.”

The purpose of a menagerie under the auspices of a zoological society can scarcely be put into better words than those found in this quotation from Sir Francis Bacon’s New Atlantis. Apt as this description of the mythical island’s collection may be, it is but a reflection of the teachings of Plato’s original legend of a perfected community, and the practical applications of these teachings by Aristotle in his Anatomy and Physiology of Animals. The history of human study shows a constant investigation of lower forms of life, ever broadening in its scope, ever more satisfying in its explanation of biologic problems and ever increasing in value from an economic standpoint.

If, however, all animals are to be subjected to “dissections and trials” there inevitably will come under observation many specimens presenting variations from the accepted mean or standard or even from an average for their kind and therefore approaching what may be called pathological.

The desire to explain the abnormal has had the effect, during the half century since Virchow defined cellular pathology and Darwin systematized the world’s knowledge of comparative biology, of directing attention to comparative pathology and of stimulating the study of 18veterinary medicine. Moreover in the past twenty-five years much work has been done and many isolated publications have appeared upon the diseases of wild animals, notably Bland-Sutton’s work, Evolution and Disease (1895), a thoroughly scientific and most charmingly written book, but rather elementary in its approach of the subject of pathology, and Wood Hutchinson’s Diseases of Animals, a more or less popularly presented treatise. I am unaware, however, of any systematic monograph upon the subject wherein we may find data showing the character of pathology in the various animal groups or the incidence of the various lesions. The reports of some zoological gardens contain the result of medical and pathological data collected for the report period. The publication of greatest merit and value is that from the Zoological Society of London, whose huge collection studied by a large official personnel makes it possible to present valuable data. The New York Zoological Park uses its material in a similar manner and has been able to explain some of the knotty problems so frequently met in wild animal collections.

Here at Philadelphia it has been our practice now for twenty years to perform an autopsy upon every mammal and bird that dies, and upon all of the large or important reptiles. There is no aquarium connected with the Garden. The office of the society keeps a record of the arrival and a general description of every animal so that a brief history of the specimen is usually available. The keepers are required to observe their charges regularly and closely and to report any abnormalities to the officials of the Garden. Somewhat detailed discussions upon signs of sickness will be given at appropriate places, where also a few remarks upon treatment will be included, but as this work is not intended to be a treatise on therapy and since this subject does not differ from that referable to domesticated animals, little space will be devoted thereto. Upon death a complete autopsy is performed and the 19findings are recorded upon a printed form from which, when the histological, bacteriological and parasitological studies have been completed, a set of cross index catalogue cards are typed; these are divided into the principal diagnoses and determinations. The report of the Zoological Society, appearing at the end of their fiscal year, February 28th, contains a résumé of the observations for the year, together with notes of interesting cases and experimental work.

There have accumulated the records of nearly six thousand autopsies and upon them as a basis has been founded the following report of the incidence and nature of pathological manifestations in the various animal groups, using also as additional data, published reports from other gardens. The book might be described as a collection of our studies, parts of which have appeared as separate articles, but most of which are entirely new, put together with as much connection as the subject matter will permit. The zoological and pathological literature has been consulted very extensively, but except for the reports of zoological societies and the publications of special students, it usually represents isolated notes by travellers and veterinarians so that many articles may have been overlooked. Therefore no claim of perfect completeness of reference is made, the statements resting chiefly upon our own records. The subject will be approached from the standpoint of description and incidence, but it is inevitable that comparisons and contrasts must be noted.

Into the realm of evolution^[1] I shall not venture because I appreciate a lack of adequate preparation for such an attempt, and because, even if such were not the case, the material at hand is lacking in data upon fishes, many kinds of reptiles and invertebrates.

20A direct and practicable application of these data will be in the direction of explaining some of the pathological states in domestic animals and man. There are indeed many disease entities or syndromes in these groups for which no useful hypothesis has been advanced, while for others a partial explanation has been offered, usually, however, inadequate wherewith to form the basis of rational prevention or therapy. Thus, for example, essential emphysema seems to be limited to the animals of civilization; on the other hand, the anatomical basis of exophthalmic goitre may be seen throughout nearly the whole animal kingdom yet the clinical phenomena belong characteristically to man, and are occasionally seen atypically in the dog. While it may be impossible to give a complete comparative anatomy and physiology for each of the pathological states, the attempt will be made to treat all subjects analogically through the zoological orders.

The experimental pathologist may find the records of the Garden useful in his work. For example, he can know that rodents are not prominent among the orders showing spontaneous arteriosclerosis, but that nephritis occurs among them in about a quarter of natural deaths; or he may learn that the Primates have a good cardiac reserve while the Marsupialia have not. Too often experimental work is not based upon facts including natural probabilities.

A collection of pathological data such as is presented in the following pages may be of assistance to veterinarians and managers of zoological gardens in the diagnosis of sickness in animals, both wild and domesticated. We do not presume to offer a system of veterinary medicine, but it is possible to introduce certain objective findings of practical hygienic and therapeutic value. Such observations are, however, limited and in our experience at the Philadelphia Garden the diagnosis of disease in a wild animal, excepting of course those which are perfectly 21self-evident, is more often speculation and conjecture than at all well grounded. It is not uncommon for animals to come to autopsy presenting a perfect galaxy of abnormalities, yet the closest antemortem observation failed to reveal unusual conduct or appearance. On the other hand specimens are frequently opened whose organs fail to contain any lesions discoverable even by careful study. Dr. Henry Chapman, sometime prosector to the Society, once made a remark in this connection—“Why do they die or how can they live so long.” Space is given to this phase of the observation of wild animals in order to emphasize the difficulties of interpreting their conditions, but of course it should be understood that certain data of value may be gained by close attention to the details of their normal behavior and to changes which occur indicating that something is wrong.

The naturalist and the trained animal keeper are, in our opinion, better judges of a wild animal’s condition than is the veterinarian, unless he be at the same time a zoologist and have long experience with a menagerie. My own observation of dogs and horses leads me to think that more acumen is needed to interpret the actions of wild animals since they seem to have greater natural reserve, and of course in regard to them there are many more variables since we see fewer specimens of each species than we know familiarly among domestic varieties. The principal objects for observation are, as in veterinary medicine, the eyes, the hair and skin, the mucous surfaces, the droppings, the condition of the abdomen, the appetite and the desire for water. Physical examination is limited to tractable beasts and those which can be caught and handled without danger to the personnel or unusual fright and damage to themselves. In the interpretations of physical signs in tractable animals, such as many ungulates and some monkeys, the experience of the trained veterinarian is of the greatest value, but this fails amongst carnivores and birds. It might be 22said that anesthetics could be used for a thorough examination, but this would be undesirable for a seriously sick animal and it is, in our experience, none too safe a procedure although often perfectly practicable. Animals do not like to be molested much as they may seem to enjoy attention, and when it is possible it is our practice to avoid handling them.

It might be contended that observations upon diseased states in captive animals would not represent natural developments, in other words, not that which occurs in the wild. Such indeed may be true in regard to the infectious diseases, but since we are imperfectly informed as to the pathology of the wild state, we are obliged to accept and use the best substitute at hand. Moreover it seems perfectly fair to consider as characteristic for an animal or group, the physical and even physiological expressions of morbid agencies as we know them, even though the animals be at the time under conditions not natural to them. It would be perhaps incorrect to say that cirrhosis of the liver occurs in .6 per cent. of animals in the wild as is the case for our autopsies, since incorrect food and infections are potent in its causation; on the other hand, our experience and some few data from naturalists and pathologists make it conceivable that tumors occur to this number in native states. The incidence of tumors in wild rodents is quite well known. Degenerations and fibroses, the result of parasitism, are known to exist throughout the entire animal kingdom. Further to illustrate how pathology is distributed in wild life, Plimmer’s experience^[2] with 500 rats (M. decumanus) might be cited. He found the following: Tubercle 3 times, tape worm cysts 10, Tryp. lewisi 49, empyema 2, tumor of jaw from old injury 1, pleuritis and hydrothorax 1. Bacteria were found in 71 rats, 40 times in the lungs, 31 times in the spleen; saccharomyces were found 16 times in the lungs. Dr. W. L. Abbott reports to us personally that he 23has repeatedly found coiled exproventricular worms in the wild specimens he has collected. Not only are we informed of some isolated and individual pathological states but the existence of epizoötics of communicable disease among wild life is well authenticated. The simple citation of the extermination of deer in one section of Colorado by pleuropneumonia will suffice to illustrate this point. Other examples are, however, interesting. The occurrence of changes in the jaw bone almost certainly those of actinomycosis is reported by Blair, the specimens being shot in the wild and believed never to have been near civilization. The white-tailed deer of the Swan River Valley in Montana, are known to be constant carriers of liver-flukes.

It would seem therefore that it is not unfair to use material gathered from animals under somewhat unnatural conditions as representing the reaction of the zoological orders to pathogenic agencies. Such conclusions must however be made very guardedly, for it is probable that not over ten per cent. of the total number of mammalian and avian species are to be observed in captivity. Because of the number of orders and the great variety of genera included in the present study it is probable nevertheless that the lesions are fairly representative of the whole animal kingdom.

However, the numbers and percentages given should be read to indicate the probabilities and should not be interpreted as implying the mortality relationships since different varieties have differing powers of resistance to the same pathological state. The margin of safety in any given group for one or several different disease entities cannot at present be stated with any degree of precision but this factor is doubtless very great. The work of physiologists suggests that there is a reserve power in the human lung sufficient to sustain life until five-sixths of the functionating organ is useless, and 24I shall quote a case of an opossum wherein only one-tenth of the respirable surface seemed to have remained; we have repeatedly seen both lungs of a monkey apparently entirely solid. Such physical vital incompatibilities might be exemplified by many other cases, but when one reviews the physiological margin of safety, inexplicable and contradictory instances are equally numerous. I have seen a male deer run a doe against the fence and butt her, without result, whereas in an apparently similar occurrence the animal would be dead in a short time. Numerous instances of slight enteritis of a short stretch of duodenum or ileum have killed, with almost nothing to be found microscopically, and on many occasions we have been chagrined in being unable to discover the cause of death. The capacity of self-healing is a variable one, but seems in direct proportion to the quietness and seclusion possible for the animal and inversely to the chance of bacterial infection.

The effect of captivity has been the subject of much speculation. For the preservation of health it would seem that animals require periods of rest and activity, thorough elimination, possibly a moderate exercise of their procreative functions, but most of all, appropriate food obtained by the physical effort we term chase. All but the very last condition is supplied in a measure in well managed collections. The degenerating effect of the absence of chase must be admitted. An interesting and suggestive example of this was noted by Mr. Jones at the London Zoological Gardens. He observed the skull of a lion that had been in captivity thirteen years, in which the canine area of the face and the part of the skull acting as the insertion for the seizing and holding muscles had undergone atrophy while the chewing muscles with their bony bases had remained normal. Numerous examples of disease atrophy are on record and those of a physical nature must have counterparts in the realm of physiology. The size to which an animal will attain 25cannot be estimated by the examples seen in menageries. Judging by the accounts of collectors and hunters and upon the more reliable of the moving picture displays of wild animals in their native haunts, it would seem probable that under normal conditions of habitat the average size of wild beasts is considerably in excess of that in park specimens.

The effect of captivity may also be felt in the direction of reduced resistance to infectious diseases. Brooks, of the New York Park, expresses the view that captivity increases susceptibility to bacteria and causes parenchymatous degenerations. In the latter direction it is interesting to learn that Seligman of London claims to have seen sudden deaths in wading and struthious birds from myocardial disease, without valvular or other lesions, for which he holds the enervating effects of captivity responsible. It is well recognized that a species may be unusually susceptible to a disease that it has not encountered in its phylogenic development. Man illustrates this peculiarity very clearly. Europeans were found exceedingly susceptible to sleeping sickness when they went first to the part of Africa inhabited by the tsetse fly, and the American Indians died in hordes when they met the tubercle bacillus for the first time. Judging by the ravages of tuberculosis in captive monkeys a similar susceptibility probably explains the matter for there are no entirely satisfactory records of this disease among them in the wild state.

In so far as general susceptibility to infection is concerned, it may be in part due to one of the artificial conditions of captivity, that of inbreeding. This influence is undoubtedly very great, both by chance in families, and by intention on the part of dealers as well as the mating which occurs in menageries. However, it is not known how far inbreeding may go in the wild state so that one must be very careful about drawing conclusions in this particular. Several years ago, at the time we reported 26the neoplasms found at the Garden, discussion arose as to the effect of inbreeding, and thereafter some observations were made in this direction. With the exception of the hyperplasias of the thyroid, not certainly of neoplastic nature, in a much mixed-up family of wolves, we could find no evidence that inbreeding was responsible for tumors. Plimmer and Murray of London, seem to imply that some of their inbred animals are likely to have tumors; reference to this matter will be made later in this book. In so far as diseases of the organic systems are concerning those of the bones seem to be the only ones in which inbreeding is significant.

The individual resistance will be reduced of course by the unsanitary surroundings incident to trapping, shipping and storage, but this need not affect the figures or pathological tendencies of classes or orders.

The effect of captivity is felt in another way. A very large percentage of wild life perishes during the first weeks or months after its capture, and in gardens the heaviest mortality occurs among the recent arrivals. The London Garden figures that from thirty-three per cent. to fifty per cent. of their total mortality is in animals that have not been in the garden six months and that die because they are not yet accustomed to their new surroundings. It seems to us, both from an academic and a practical standpoint, that this is a long time and should afford ample opportunity for the garden to study the specimen and for the specimen to become acclimated. These early deaths are perhaps to be ascribed in large part to failure of acclimatization but many are doubtless the result of infection acquired in the wild, in transit while in the hold of vessels, at quarantine, or in trains, or at the establishments of dealers. We have seen a few deaths which have followed behavior that might be likened to homesickness. Perhaps the age at arrival has an influence upon the morbidity and mortality of wild animals, for it is easily 27conceivable that the young and the very old might adapt themselves to new surroundings with much less readiness than the sturdy middle-aged adult. The age of animals upon arrival is very rarely known, and can only be recorded as “young,” “fully developed,” and “old.” This will have an effect upon statistics and when possible is noted in the text, but this is not practicable to the extent we desire. The meaning of “young,” “adult,” and “old” is not the same throughout the animal orders nor even within orders.

Mitchell^[3] has attempted to gain concrete ideas of the expectancy of life among animals by analyzing the records of the London Gardens. This gentleman bases his figures upon known ages and the length of time in captivity, from a combination of which data the specific viability and the potential longevity may be estimated. Such results, he admits, can only be approximate and they show within classes and orders, a decided lack of uniformity. The terms “specific” and “potential” longevity, coined by Sir Ray Lankester, apply, for the first, to the average length of life as it is affected by external conditions and those incident to procreation, while, if an animal be under ideal conditions it will attain the potential longevity which is longer than the former. These considerations have a biological and economic importance, while a knowledge of the pathology shown by the various groups may help to explain these durations of life. Contrariwise figures of the expected longevity may assist us in evaluating youth and senility in the causes of death but can hardly affect the comparative nature of the lesion.

A résumé of Mitchell’s studies indicates that the higher apes have a potential longevity and a hardihood much less than man but still upwards of thirty years. As one investigates lower in monkeys, life periods become shorter, while in the next order, Lemures, the length of 28life rises. Carnivora have a reasonably good vitality, their potential periods varying from ten years in the foxes to thirty-three years in bears. Insect eating animals are short lived, three years being a maximum. The Bat family shows great variations, the greatest life being not over seventeen years. The Rodentia have long lives compared to their sizes—twenty years in porcupines, fifteen years in squirrels, thirteen in marmots, nine in agoutis and capybaras, and three in dormice (which is also about the maximum for the rat). Hyraces live four years on the average. Proboscidea, although reputed to live to great age, probably rarely live a half century and may be said to have an expectancy of twenty to thirty years. Perissodactyla (horses, tapirs and rhinoceroses) while they may live half a century, have an average life of between fifteen and thirty years. The closely related Artiodactyla fall into two groups, a first comprising antelopes, sheep, goats and deer which rarely exceed seventeen years, and a second consisting of cattle, camels and giraffes, which vary in expectancy from eighteen to thirty years. The smaller members of the Ungulata have in relation to size a relatively greater viability, the ruminants, however, having on the whole a low viability. Marsupials vary from a maximum of seven years in the opossum to eighteen in the wombats, but none of this group has a good viability. The Aves as a class or if compared according to dietary requirements, have longer potential ages and better viability than mammals. Passerine birds average twenty years and many live to sixty, while the Picariæ approach the former figure but do not have such good viability. Psittaci and Striges may live a half century but the resistance of the latter is much reduced by any unfavorable surroundings. The raptatory birds live fifty years, but their viability is variable. Herodiones have a maximum expectancy of thirty years and good resistance, while their relatives, Steganopodes, may live fifty years, and Odontoglossæ have a good 29viability, up to twenty years. Anserine birds may live to be fifty, and, unless conditions are quite unfavorable, have a good resistance. Columbæ may under good conditions live to be fifty. Gallinaceous birds may only be expected to survive twenty years, a figure also given for Fulicariæ. Alectorides may live up to fifty years. Limicolæ, though they do not thrive in captivity, may live thirty years. Impennes live poorly under artificial conditions, the greatest record being twelve years, a figure also holding for Crypturi. Struthiones, if the conditions be right, may live fifty years.

Because of the variable specific longevities, it is frequently difficult to decide when an animal is senile. Man is said to be as old as his arteries, and his span of life nowadays is in the neighborhood of half a century. Parrots exhibit lesions of the vascular system comparable to the arteriocapillary fibrosis of human beings, and their expected longevity is about the same or a little greater. From a study of our cases of this lesion in parrots it can be said to appear quite early in life and not to lead to organic disease as it is alleged to do in man. It is, however, interesting to note that in those animals which are supposed to have the longest specific lives—elephants, snakes, anserine and raptatory birds, parrots—there is relatively low mortality and fewer infectious diseases are encountered. The last part of this statement should be qualified by stating that anserine birds and parrots are quite susceptible to mycoses, in all probability from musty food, which raises their death rate, but as this is accidental and artificial, it can be excluded from consideration.

In a rough way there is a direct relationship between the size of an animal and its longevity, but this is not close enough to be a reliable guide; whales and elephants live a long time, but so do snakes and parrots. Within orders this relation of size and expected longevity is more easily seen but is not absolute. I cannot state, according to my 30present studies, that there is an unqualified relationship between the size and expected longevity of an animal and its pathological lesions.

The immediate surroundings and the management of captive animals have a very direct and important bearing upon the mortality and perhaps upon the incidence of morbid processes but probably not upon the character of the latter. A full knowledge on the part of the personnel of a zoological society concerning the habits and habitat of every animal in their keeping is essential, to which must be added a group of interested keepers. In engaging the last, it should not be forgotten that certain men have “a way” with animals and that others cannot manage themselves.

The enormous literature at the disposal of the naturalists permits executive officers to formulate a plan of housing and feeding with fair accuracy for each kind of animal, but of course it is rarely possible to obtain in sufficient quantity the natural food (e.g., ants for anteaters). In so far as food is concerned it seems that with a few exceptions like the one just mentioned, the substitutions made at the zoological gardens are nearly satisfactory. The elements in which the captive diet is poor are the inorganic salts and vitamins since Dr. Corson-White, some of whose work is included in a later chapter, has shown that for those animals which our statistics indicate as most prone to have rickets and osteomalacia, the available phosphorus and calcium are low, and one vitamin was also below the desired quantity. In this regard, however, I am not at all convinced that diet alone will suffice to explain these degenerative osseous diseases; I shall take this up more fully later. Careful inspection of all food should be made and cleanliness (sifting of cereals, protection of meat from flies, etc.), is indispensable. The mortality among our carnivora has materially decreased since the horse meat after butchering was placed in covered galvanized iron pans. There 31are many problems of feeding, too numerous to be covered in a survey of this sort, which must be solved, and it is a credit to superintendents that this they have studied carefully.

There are two problems in the management of animals upon which much difference of opinion exists, namely the heating of houses and the material of which cages are made. It seems to be the practice in many gardens to keep animals very warm. Dr. Chalmers Mitchell states unqualifiedly that adult animals do not have to be kept warm, and that even an equable temperature is not demanded, variations in temperature having a distinctly stimulating effect. However he maintains that they should be kept dry and must be supplied with a shelter. This is in accord with the experience at the Philadelphia Garden, since for many years we have allowed access to the open air all winter to every animal that could stand it. A large group of macaques has now lived entirely in an open “band stand” cage for nine years with a lower mortality than in the rest of the monkey collection, which is permitted to go indoors some of the time. Occasionally one in poor health is frozen to death, and healthy ones may lose fingers, toes, or a part of the tail, but the general condition is so much improved that they present an attractive exhibit to visitors. Unless a storm be of great severity, wild animals are usually indifferent to it although they may seek their shelter. Snow apparently is no source of fear to them, and many enjoy playing in it. The general principles of the enclosure should be proper lighting, free access of air, dryness and shelter in time of storm, the last so arranged that the sleeping place is well protected. Appropriate arrangements should be made for nocturnal animals, regardless of their visibility to visitors, if their preservation is of importance.

The hygiene of communicable disease has influenced everyone to use concrete and metal for cages. These substances 32are without doubt most simply kept clean, but they are heat-conducting and remain cold or damp longer than wood or the ground. It may be claimed that the latter two cannot be disinfected so well, but this need not militate against their use. Wood can be disinfected by sunlight or by mechanical cleaning plus disinfectants, by a blast lamp and by paint. The ground will disinfect itself if allowed to lie fallow for a time, or it may be turned over after sprinkling with lime. It is fair to note that the New York Zoological Garden reduced their mortality, especially from verminous pneumonia, by changing some deer herds to concrete paved enclosures; if that were the only change made the result would be very significant, but it should not be forgotten that another clean ground range might have served as well to a herd from which the infected ones had died. My own observations with guinea-pigs, rabbits, mice and dogs lead me to believe that they thrive and breed better on wooden floors than on metal or stone.

I have tried to work out figures to show that more animals die when housed in enclosures of stone and metal than when upon the earth or on wood, but the attempt has been unsuccessful chiefly because of the presence of epidemics and parasites, principally among the birds. The attempt was further embarrassed because some members of an order are housed on both floorings. However, there was no great advantage for the metal and concrete floors even after the epidemic had been discounted. This Garden does not have a great number of pneumonias, a disease said to be favored by dampness and cold, but those that occur are chiefly among the small mammals, on wooden floors and in the large bird house in cages of concrete and metal. However, the construction of both these houses permits the visitors to approach very close to the cage, a factor that doubtless explains the disproportionate incidence of inflammation of the lungs. In so far as outdoor fowl and ungulate ranges are concerned, they 33should be changed frequently under the best conditions since occasionally one will find groups doing badly until moved. Moreover the ground becomes contaminated with parasites such as esophagostomum and heterakis, infestation with which while not very serious in itself, may lead to fatal infection with bacteria.

The effect of animal parasites upon the morbidity and mortality of wild beasts and birds in captivity is by no means clear, and Doctor Weidman and I are inclined to be sceptical, with certain reservations of course, of their great importance in the death rate. Doctor Weidman has kindly agreed to contribute a chapter upon the general distribution of protozoal and metazoal parasites with a summary of their probable pathogenic importance.

The groups known to have a decided pathological power might be divided into the toxic, the tumor formers and the mechanically obstructive; certain parasites have properties placing them in two of these classes. The first group comprises the hemosporidia and hemogregarines, the uncinaria and some of the cestodes, forms which produce hemolysis and hemorrhages with varying grades of anemia. The importance of this group is shown chiefly among the Aves, in which high grades of anemia are occasionally met from malarial infections, but cats and dogs or even herbivores also frequently suffer from hookworm. The tumor-producers are chiefly echinococcus worms, the cysts of which may grow large enough to occupy nearly the entire abdomen. A certain grade of anemia and general ill health accompany this hydatid disease, partly the result of a toxin and partly by damage to important viscera. Those parasites which obstruct mechanically do so by their own bulk or by an accompanying inflammation, incited by them as foreign bodies or by bacteria which have gained entrance at the irritated point. This is exemplified by the enormous collection of nematodes sometimes found in reptiles (a pailful was removed from a python) and by the tightly coiled or 34tangled thread and tape worms frequently found in birds. The effect of swelling by the mucous membrane under the influence of worms is illustrated by the infestation of the proventricle in parrots. Here spiroptera penetrate into and under the glandular layer which swells and pours out mucus, the total mass of nematodes, mucus and tissue obstructing the passage.

Very many animals show parasitic infestation at postmortem, but the percentage in which they can be said to be principal causes of death is quite small, while that in which they play a rôle as activator of the terminal condition is also small but indeterminate. The latter group comprise, together with the anemias mentioned above, certain forms of pneumonia, of hepatic and vascular lesions. Inflammations of the lungs from ascaris and paragonimus are fairly well known; fortunately we have been troubled less with this than have most gardens, possibly because we do not have such large herds of herbivora susceptible to it. Hepatic diseases from flukes, from coccidia and from amœbæ we have always with us in small numbers, but they are unimportant excepting enterohepatitis, a condition which appears in nearly all orders. This last disease, be it purely amœbic as in dysentery of man and monkeys, or like blackhead of turkeys and chickens or in the forms of quail disease, arrests the attention at once and evokes a desire to explain the association of large intestines and liver. Parasitic vascular lesions are relatively unimportant.

Taking parasitic infestations by and large, there are close similarities throughout the entire animal kingdom, and the effects produced by a given genus will be repeated almost exactly in several others. The pathological pictures of anemia, of hepatic degeneration, of cystic degeneration, of colonic ulceration or of fibroses are similar in different hosts, only slight variations in the type of inflammation being noted, for instance in reptiles and birds as against the mammals. We have made rather close 35observations upon the effect of parasites in the production of neoplasms, incited by Fibiger’s discovery of nematodes in the rat’s stomach cancer, but, with the possible exception of a papillomatous growth in the stomach of opossums from the action (?) of physaloptera, we have been unable to establish such an etiological relationship. A decision of the importance of parasites in any given case is not without its difficulty, and we are inclined to reserve judgment pending further analysis unless the effect of the invaders is unequivocal. Leiper^[4] does not seem to credit animal parasites with a great effect on the mortality after a specimen has been in the collection six months since all the intestinal varieties he studied came from animals dying in that period. On the other hand the forms which invaded the internal organs and tissues were, in his series, from specimens resident several years in the garden. He seems to think the conditions of life at the garden favor the expulsion of intestinal worms. To what extent some intestinal worms may be commensal remains as uncertain as the value of certain bacteria in the gut tract. In man considerable importance has been ascribed to certain fermentative and putrefactive germs in the maintenance of a reaction unfavorable to strict pathogens and some observers have looked at them as possessing a digestive power. In the digestive tract of the animals eating large quantities of carbohydrate as cellulose, nature provides for its use by rumination and by supplying a large hind-gut, by which means secondary mastication and bacterial decomposition of the cellulose capsule insures its full use. Possibly a similar usefulness may be finally ascribed to some animal microbes or even larger metozoa.

The rôle of vegetable parasites in the causation of disease among wild animals seems as undoubted as it is in the human being and the pathologic results are usually as 36clear, at least for the entities of which we have exact data, based upon comparisons with man and domestic animals.

There seems to be no essential difference among mammals between the pathological pictures of infectious septicemias, the mucous and serous membrane inflammations and tuberculosis for example. They are characterized by fibrinous, purulent or infiltrative inflammations which may go on to necrosis or repair, by fever, by leucocytosis and by evidences of resistance—all of these things occurring in a similar way throughout the class. Of course not all animals are receptive to all infections since specific racial and generic immunities exist, but the basic response in terms of pathology is similar. There are no normal means of judging the susceptibility of wild animals on their native heath to the important pathogens of civilization, pneumococci, streptococci, staphylococci, cholera bacilli, the typhocolon group, the Friedlander group and others, but it is interesting to note that in captive conditions they evince some receptivity to these germs or their congeners. The pneumococcus takes a fairly heavy toll in zoological collections every year and the Friedlander bacillus, not a very common cause of human pneumonitis, has been seen here and at London.

Among the birds, however, quite distinct differences in some pathological processes occur, not only from the mammals but also within the class. As a whole birds do not produce pus as we know it in man, probably because of the absence from their leucocytes of a protein-splitting ferment; their leucocyte-producing organs do not seem to respond as readily to a virus, the place of purulent exudate being taken by a coagulum or necrosis. The former varies from a clear gelatin-like material seen upon serous surfaces to a thick mat or mass of coarse but short fibrinous strands. Necrosis may succeed upon the latter or occur so promptly as to appear like the original form of 37degeneration. It is usually rapid, accompanied by a circumferential congestion but not associated with active phagocytosis. Giant cell production is variable, but when developed the appearance is like that of large syncytia. Hemolysis is not marked in the simple infections but a hyperplasia of the mononuclear nodes of the liver is the rule. The function of this nodal increase is not quite clear. It has been always thought that the scanty bone marrow would supply the necessary erythrocytes, but we have seen these mononuclear areas full of pale red cells fitted with round nuclei and without pigment. The fibrin mentioned above does not have the delicate interweaving that we know in a fibrinous exudate in man. This is interesting when we consider the composition of the blood and its coagulation in the Aves. The cell upon which human coagulation seems to depend, the platelet, is represented in birds by the thrombocyte, which appears only up to about 50,000 per cubic millimetre. Coagulation time is relatively short and the resulting clot is firm and irregular. Perhaps this may have something to do with the nature of an inflammatory exudate.

The response to infection on the part of birds may to some extent depend upon differences in anatomy, which are quite distinct, not only from the mammals within which class the anatomy is more uniform, but also from one avian order to another. These differences among the birds may be exemplified by the large foramina between lungs and air sacs in the water birds, a passage which permits infection, notably mycosis, to spread from the first to the second. Again the close apposition of the pancreas to the duodenum over a long stretch permits easy infection of the former from the latter. Still again the large renal-portal vein in the gallinaceous birds explains some of the infections of the liver secondary to intestinal disease. The position of the lungs, deep in the thorax and fitted into recesses made by the sharp anterior border of the ribs and overlaid anteriorly 38by a rather firm air sac wall, makes it difficult for these organs to expand and therefore renders even a simple congestion a dangerous thing. The position of the ovary subjects the shell-less egg to much danger from the intestinal area.

These and many other peculiarities of anatomy affect the pathological picture in birds. To be sure there are also noteworthy differences among the Mammalia, notably in the intestinal and genital tracts, but the pathologic response is not so varied as in the birds. When due allowance is made for the kind of stomach and absorptive area, apparent differences can be reconciled. For example, there is little confusion experienced in comparing acute erosive gastritis or the follicular enteritis of an omnivorous intestinal tract (man or pig), of a sacculated stomach and absorptive tract (the marsupial), of a carnivorous gut (cat) or a herbivorous compound stomach with its long digestive and water-absorbing surface (cow or camel) and an expansive muscular organ with a very extensive digestive area (seal). The type of lesion seems the same, in that inflammation, pus, necrosis, granulation tissue and cicatrices are comparable throughout the series. The size of the hind-gut has been taken by Metchnikoff as an indicator of the possibility of intoxication by degradation products of digestion. He believes that the capacious colon of herbivora and the short small one in carnivora explain the relatively greater life in the latter, because here less stagnation and absorption can take place. A reference to the expected lengths of life given before hardly substantiates this, and in our later chapters there will be found no strong indication that animals with large colons suffer with degenerative visceral changes more than those with small ones; nay even the reverse may be found true.

In regard to epizoötics the behavior of man and lower animals is similar except perhaps that during an outbreak a smaller percentage of the latter give evidence of individual 39immunity and whole groups are apt to be carried off. Occasionally hygienic measures stay the ravages, at other times nothing seems to avail. Fortunately it is sometimes possible to sacrifice infective specimens and remove contagion. We have had few serious outbreaks, unless one might call our former heavy infection with tuberculosis in monkeys an epizoötic. The principal ones were an unexplained water fowl disease which carried off one hundred and forty-six birds, an imported epizoötic of quail disease which killed about the same number, a few cases of blackhead among wild turkeys, and a small group of cases of amœbic dysentery in monkeys and of thrush in passerine birds, and a small number of tuberculous pneumonias in snakes.

Pathology may be difficult upon an anatomical basis, but when we engage to explain functional physiological defects we are surely embarked, with a poor compass and weak rudder, upon an uncharted sea. One knows, of course, that all animals require the same amount of food elements per kilo of body weight, that man eliminates his nitrogen as urea and uric acid, that monkeys do the same, that most other mammals destroy uric acid and excrete allantoin, that birds and reptiles form uric acid but chiefly urates, that there is an adaptation of alimentary tract and diet, that herbivores have a high threshold for carbohydrates, that there is a variable quantity of enzyme present in different organs and in different animals, that vitamins, whatever they may be, are necessary for the growth of young animals, that hormones exist whereby correlations of parts are kept normal—but these things, rather than being learned thoroughly from animals, have merely been substantiated by comparisons with man. Constitutional diseases so-called, from which the necessity to investigate much of this physiology originated, are little known in the wild animal. Many cases of so-called gout have been encountered and we have seen an instance of diabetes in a fox, but more extensive 40experience is needed for definite practical comparisons. This applies to thyroid and pituitary disorders and to the vague conditions we have at times been obliged to call marasmus or inanition.

Some attention has been given to the study of diets for the wild specimens of our Garden, but no systematic observations have been made or records kept upon purely physiological subjects. Reference will be made at appropriate places to accepted comparative physiological facts, but our statistics permit additions to such knowledge only in a limited manner and in isolated instances. Doctor Corson-White has very ably summarized the diet, alimentary tract and physiology of the zoological groups with the pathology as found in our records.

A word might be added here as to the destruction of animals by injury from fighting and harassment by others in the cage. Fighting doubtless causes death, especially when males are together, but it is our experience that in cases of traumatic death search should always be made to see if the resistance of the dead animal had not been reduced by some disease. This is well illustrated in birds. Very frequently a specimen will come to autopsy with its head feathers plucked out, or with a billthrust in the wing or pelvic region. Such birds are not infrequently suffering from malaria, or heavy intestinal parasitism or from organic disease whereby the resistance and self-preservatory power has been decreased.

The foregoing survey of the approach to our subject reveals the multiplicity of factors which affect the study of comparative pathology. No one of them can be entirely omitted, no one is without some effect upon the origin and expression of disease, and no one is fully understood. Yet it is to be hoped that a study of our material, accumulated under routine conditions and uninfluenced by any experimental procedures, will demonstrate the natural response of various zoological groups to morbific agencies. Perhaps reactively some of the modifying 41conditions may thus be understood. It is also not unreasonable to expect that alterations observed as natural responses in a large number of specimens in nearly normal surroundings would serve as more reliable guides to investigative speculation than would changes in a few animals under artificial technical experimentation. We hope that the few facts we have been able to record may afford someone a basis for further biological studies. It is also to be hoped that something has been learned which in the end will afford an explanation of the diseases of man. Too great optimism in this direction should be guarded against because the human being is indeed an animal sui generis and, from the standpoint of normal conditions of nature, a wild animal.

The zoological classification found on pages 43–46 was compiled in 1903 by Dr. A. E. Brown on the basis of the British System. With a few exceptions the computations in the text are made on the basis of zoological orders since the number of specimens in families is often too small and the complications of so many different figures would be confusing. The tables will be found to correspond to the sequence of the classification. Dr. Corson-White has, however, used for her analysis the dietary groupings. A carnivore in her chapter implies strictly a meat-eater, in the rest of the book one of the zoological group Carnivora.

The Laboratory of Comparative Pathology at this Garden speaks for the earnest desire on the part of the Directors to use the material to its fullest extent, and I, acting for myself and my associates, wish to record our appreciation of the facilities offered to us for study, and for the broad-minded, scientific coöperation the Board has always displayed. The President, Charles B. Penrose, M.D., Ph.D., LL.D., was the active originator of the plan whereby this department was started, and he has given to it continuously the support of his rich experience. I wish to express for myself the deepest appreciation of his 42personal interest in my studies, and assistance which has been constructive and stimulating. Whether or not this present work prove useful to the extent that is hoped, the results from the Laboratory are such as to make the scientific world debtor to this gentleman.

It is a duty, and a pleasant one, to record, though unfortunately in memoriam, my association with Arthur Erwin Brown, A.M., Sc.D., Ph.D., C.M.L.Z.S., for many years the Secretary of the Society and Executive Officer of the Garden. Doctor Brown as teacher was ever ready to help in the broad subject of biology, and I am proud to recall that he guided me also as a friend.

The first director of the Laboratory was Courtland Y. White, A.M., M.D., who served from 1901 to 1906, retiring then to accept a position in the City Laboratory. The foundation of the recording system is still in use essentially unchanged from his plan, and is a credit to his foresight. Our clerk and technician, Miss Harriet M. Phelps, has served the Garden faithfully and well since 1906. The condition of the museum is very much due to her interest and watchfulness. Thanks and appreciation for her work are felt by every one, the author most of all. Dr. F. D. Weidman has been our first assistant since 1911, and his work on parasitology has been of the greatest value, practically and scientifically. It is to be hoped that we shall be able to retain him indefinitely. Dr. E. P. Corson-White has in recent years taken an assistant position with us, armed for the work with a thorough knowledge of applied organic chemistry and immunology, and has already obtained useful results.

SECTION II DISEASES OF THE HEART — Expression of Cardiac Disease. — Coronary Artery Disease. — Kinds of Pathological Change. — Degenerations and Inflammations. — Endocarditis, Myocarditis. — Unusual Pericardial Changes. — Hypertrophy and Dilatation. — Summary of Lesions Associated with Hypertrophy and Dilatation. — Comparison of Mammalia and Aves. — Avian Hypertrophy. — Summary.

The heart is an organ whose duty, throughout the two classes considered in this study, remains entirely identic, purely a physical one in driving the blood through the corresponding vascular system. The physics involved naturally differs between mammals and birds, but energy is derived from the automatic power lodged in the cardiac musculature. Whether this be neuromyogenic, as seems to be the case in all mammals, or purely myogenic, as is probably the case for the birds in which MacKenzie and Robertson^[5] say there is no atrioventricular bundle, the result is the same, since in both classes there is some continuity of muscle fibres from auricle to ventricle. The gross anatomy varies little if any more than the physiology, albeit there is proportionately greater auricular capacity in the mammals than in the birds, and indeed there are differences within the classes which cannot now be readily explained; certain minor variations of valvular arrangement exist, such as the absence of the membranous light tricuspid in Aves.

When, however, one considers the cardiac power available for various animals, the subject becomes one of greater breadth and complexity, for no consistency obtains even within families, since the demand for cardiac strength will vary more with habits than with zoological relationships. Thus for example the domestic rabbit has a small heart volume while the wild hare has a great one. Although, of course, the size of an organ may not be an absolute measure of its efficiency (a flea’s leg muscle has relatively greater power than a man’s), yet size is the only physical gauge one has for estimating nature’s preparation for expected demand. Perhaps this 49will be shown later when after discussing the pathological anatomy of the heart in the wild mammals and birds, we can study these changes in light of statistics upon the relative size of the heart.

The diseases of this organ are known only by their physical effects, chiefly by causing physical or functional defects in other organs and to a minor degree by purely physiological irregularities in the heart itself (tachycardia, arrhythmia). All the latter and most of the former are subjects discovered by observation during life and unfortunately cannot be included in the study at hand. Both states are well known to the veterinarian who diagnoses them with reasonable ease in animals that can be handled; I saw one case of arrhythmia in a monkey for which no adequate gross morbid explanation was found postmortem. Some of these functional abnormalities are certainly caused by myocardial disease and cardiac failure has occurred among many orders. An interesting observation was made by Plimmer^[6] on several large birds (ostriches, storks, cassowaries) which apparently died from this condition; at autopsy he found myocardial degeneration, or epicardial edema or only a flabby heart. Lack of exercise was held responsible by this observer. Such cardiac deaths have probably been encountered at this Garden but we have accounted them to shock, or gastrointestinal disease; this matter will be discussed on a later page.

If a degenerative sclerosis of coronary vessels be the cause of angina pectoris then perhaps paroxysms of this kind occur, for we have seen such anatomical changes in the heart of three widely separated varieties of animals, a Nylghaie, a Hamadryas Baboon, a Macaque, and a Brown Pelican. The history of these animals does not 50register anything resembling the clinical picture of angina pectoris in man, and they did not come to their death from the arterial changes in the heart alone since sufficient other pathology also existed.

As an introduction to the strict pathology of the heart it might be well to outline the headings of the scheme upon which it seems desirable to study the subject. It is hardly profitable to take up seriatim the ordinary general pathological processes as discussed in systems of pathology for it is our purpose to show the distribution of basic aberrations from the normal in terms of zoological position. To this end one must consider the response of the heart (a) to damaging influences and (b) to a demand for increased work. In the first group come degenerations and inflammations, upon which may succeed an incompetency in the form of dilatation. The response of the normal heart to any physical demand greater than customary has usually been thought to lie in the direction of hypertrophy, but on occasion it has seemed to be in the form of dilatation, especially if the strain has been sudden and severe. Starling thinks that the primary and normal reaction of the heart to physical strain is always dilatation. The idea of hypertrophy must not be confused with an understanding of the relatively large hearts in animals whose habits demand great cardiac power, for then it is their norm and might be called “physiological cardiac hyperplasia.” I shall use the terms “increased muscle bulk” and “increased chamber space” as preferable to hypertrophy and dilatation; this also focuses attention upon the two features of an enlarged heart.

Degenerative changes in disease are recorded in our system as amyloid, hyaline, fatty metamorphosis, granular and cloudy degeneration. While there is perhaps between some of these conditions and true myocarditis a matter only of degree, the records have been analyzed as filed and perhaps some lessons can be learned from the responses of the various zoological orders. In the accompanying Table 1 will be found the distribution of degenerative and inflammatory lesions through the zoological orders. The percentages speak for themselves but deserve as well some consideration from the standpoint of normal heart value; this will be taken up later after the other lesions have been discussed.

In this and subsequent tables, figures in italics are for small groups of animals coming to autopsy, usually less than one hundred, and from which percentages may be misleading. The number of autopsies upon such groups may be found by consulting the list given on page 47.

Romberg said in his classical work on the heart that there is always some form of myocardial disease with endocarditis. The 44 cases of valvular disease detected at this Garden are 15 of chronic nature, 29 of acute or subacute character. In the former, the chronic, 9 showed some grade of muscular involvement, while 21 of the 29 acute cases of valvular inflammation were accompanied by myocardial damage; the percentages are 60 for chronic and 72 for acute, a relation that would be expected if one credit the theory that many valvular inflammations start at the root of the valves, but, at all events, they indicate that after the acute stages have passed the myocardial damage may be repaired.

Fig. 1.—VEGETATIVE AND ULCERATIVE ENDOCARDITIS OF AORTIC VALVE. OSTRICH (STRUTHIO AUSTRALIS). ORGANISMS ISOLATED CORRESPONDED CLOSELY TO BAC. AFANASIEFFICHESTER.

53The large number of cases of endocarditis among the Carnivora, Accipitres, Anseres and Marsupialia is noteworthy and can hardly be explained by other argument than a special vulnerability of this organ in these groups. However, the unusual number of cases in our only native marsupial, the opossum, seems worthy of a special note since ten of the twelve instances in the order Marsupialia affected this particular animal. When seen these ten cases were acute in five instances, subacute in three and chronic in two. The Streptococcus pyogenes was isolated in three of the five acute cases; bacteriology of the others was negative or not done. All of the acute and one of the subacute cases were combined with some evidence of general septicemia. The type of lesion was in no way peculiar, unless the facts that all were vegetative when acute and markedly deforming when chronic, be noteworthy. In two chronic aortic cases the valvular orifice was almost closed, yet the left ventricle could not be considered as greatly hypertrophied and no dilatation existed. In one acute aortic and mitral case, general dilatation existed. The mitral was involved nine times, three times alone, four times with the aortic, once each with the tricuspid and pulmonary. Once the vegetations were limited to the mural endocardium. Nine of these animals came from one enclosure over a period of two and a half years, during which time other opossums died from similar bacterial infections (pneumonia) despite repeated cleansing of the place. No unusual number of cases of this or similar kinds occurred elsewhere in the Garden at this time, but it would seem that we had in this cage a continued bacterial infection.

The appearance of a stiff gelatinous exudate in the pericardial sac has attracted our attention on ten occasions (8 birds, 2 mammals). The substance seems quite homogeneous and almost entirely acellular. One specimen became solid on heating and another became turbid when put into Kaiserling’s fluid. In two cases bacterial cultures were made; nothing grew. It has not been associated with tuberculosis or tumors nor has any one pathological lesion more than another appeared to accompany it.

A peculiar lesion occasionally seen in birds is “uratic pericarditis” a process not infectious at all, according to Plimmer, but due to renal disease. It has been seen here in association with retention of urates in the kidney, with gout of birds, and apparently quite independent of any renal or constitutional disease. Both layers of the sac 54are pearl gray or irregularly salted with a whitish granular material so that they are entirely opaque; occasionally the distribution is spotty. The deposit does not seem to penetrate the myocardium. There is at times some involvement of other serosæ, but this is usually much less marked than around the heart. It does not seem that this of itself should be fatal, but it has been the most decided pathological factor in some of the autopsies.

Aside from pericarditic exudates, twenty-one instances of pericardial effusion have been encountered. They offer little that is peculiar in etiology, chemistry or cytology, but as there has been some question of the position of the accumulation of the fluid in human beings, it might be well to note the position in our material. It is recognized in veterinary medicine that the cardiac dullness is increased especially to the right, and that most of the fluid will be on that side and posteriorly. At our autopsies on mammals this is the position usually occupied by the fluid, the apex being covered by pericardium, unless the quantity be great enough to make the sac taut, and this position is retained whether the animal be laid upon the one side or the other; nor does the fluid all leave the base of the heart when the body is placed prone. The crown of the heart is nearly always well covered. In birds, on the other hand, the fluid occupies the apical part of the sac, probably due to the fact that this membrane is attached by its tip to the transverse air sac wall which takes the place of a diaphragm, so that the tip of the heart is always free and the pericardium of the base fairly closely applied to the epicardium. This holds good even for the birds whose cardiac apex is normally attached to the pericardium by a fibrous band.

The response of the heart to a continued demand upon its working capacity will, as already indicated, lead to increased muscle bulk or to larger chamber size. Whether 55hypertrophy be purely the building of a bigger engine or be accompanied by, or due to, muscular disease as had been suggested by certain authors, was a question to which an answer was hoped, but it would seem that the solution is no nearer than can be obtained in human pathology. Fifteen of the 34 cases showed some degree of myocardial damage. Some of the other cases may have been instances of so-called essential hypertrophy, enlargements due to hard work or to low grade hidden infection. Aubertin^[8] ascribes such cardiac muscle increase to overwork under the stimulus of intoxication from intestinal sources or from irregular constitutional functions. For information concerning this and pathological enlargements one may consult the Table (2) of Hypertrophies and Dilatations; in advance the method of charting must be known. Since it is usually impossible to decide what may be the single important factor in the cardiac disease, all of the accredited factors have been listed with the hope that the resulting figures would be significant. Thus an animal may have recorded pericarditis, nephritis and arteriosclerosis—who shall say which was primary or most potent in the cardiac change.

Essential hypertrophy is limited to those cases for which there was no concomitant pathology that might have been responsible for the overgrowth. There was one in a carnivore (fox) and one in a raptatory bird (buzzard). Idiopathic dilatations on the other hand are much more common, but they still bear a relation to the apparent vulnerability of the heart. Their distribution is as follows: Primates 1, Carnivora 1, Pinnipedia 1, Ungulata 1, Marsupialia 4, Anseres 1. These may be cases such as Plimmer described, of cardiac failure, indicated by dilatation, the result of inactivity. Besides these special instances and the ones accounted for in the list, there were three acute dilatations apparently due to shock, 56two ungulates and one marsupial, probably incidental to fright when being caught by the keepers.

The association of secondary dilatation with hypertrophy is only evident in three instances. One case and perhaps the most interesting, is that in which the principal antecedent pathology was thyroid hyperplasia and nephritis; the dilatation was perhaps agonal or shortly before the last struggles. It would seem that all of the dilatations occurred shortly before death because long standing passive congestions and dropsies of cardiac origin are exceedingly rare; only one certain case is recorded (carnivore).

Let us now examine the Table (2) according to orders and then as to causation. The Primates’ heart is apparently well able to increase in size in response to increased work, a demand most often made by pulmonary, pleural and pericardial diseases. Two of these cases occurred in animals suffering with pulmonary tuberculosis sufficiently extensive to impede cardiac action while in another case the tuberculous lesion was mild but a pericarditis existed. When the right hand columns are inspected it would seem that on occasion dilatation may occur; one of the tuberculous pulmonary cases had a dilated heart. The slothful lemurs apparently have no call upon their cardiac mechanism.

Carnivora with their large organ, which, it would seem, should be prepared for excess work either simply as a reserve or as an inherent ability to grow, present in about equal numbers, hypertrophy and dilatation. It is admitted that there are within this order, genera of differing habits, but analysis of the canidæ, felidæ and ursidæ for examples, in the first place, offer too few specimens for conclusions and, secondly, have upon trial actually shown nothing definite, so that we are forced to use the larger group, the order. It is interesting to note that long continued infection is in this order the most potent factor in enlargements of the heart. Four of the ten cases show myocarditis. Nephritis does not seem very important in relation to cardiac muscular increase, but occurs with great frequency in association with dilatation. Three of the cases of hypertrophy were associated with thyroid disease and two of these showed dilatation as well. The general causes of chamber distention are more diverse, and we see associations that do not appear with hypertrophy, namely arteriosclerosis and diseases of the chest.

58The rodents seem to have no power to increase muscle bulk, but a sufficient number of cases of dilatation occur to make one conclude that this is their method of response to unusual strain. Pulmonary disease, mostly of infectious nature, and myocardial degenerations are the principal causes.

The next order to show cardiac enlargement is the Ungulata where nephritis is the most frequent association with hypertrophy and disease of the pleura and pericardium with dilatation, or the reverse of the factor value in the Carnivora. These animals, fairly well prepared for flight, with moderately large hearts, seem more often to show dilatation than hypertrophy.

Two Edentata (armadillo) showed dilatation but no hypertrophy.

Marsupials behave somewhat like rodents in that the heart does not seem to increase muscle bulk, but our records do not explain this clearly. As already mentioned four cases had no sufficient internal reason for dilatation, but as one was probably the result of shock three only remain to be accounted for. Nephritis seemed to exist in all three, but two of them had kangaroo mycosis of the jaw and a general chronic infection.

If now our attention be given to the Aves we find the highly specialized Passeres and Striges not represented and their closely related well-organized orders Picariæ and Psittaci with only an isolated single case. This is the more interesting since the last order suffers reasonably 59often with arteriosclerosis. Accipitres, the birds of pugnacious habit and carnivorous diet, seem well able to increase their muscle upon demand, but do not often suffer dilatation. Vascular and renal diseases stand out most prominently in the etiology, and one-half of them show myocardial change. The Galli, which includes both ground and flying birds, are represented but fail to exhibit any unusual accompanying disease. Anserine birds apparently have a low power to increase the size of the heart, but most often allow it to dilate. Struthiones, large stalking and rapidly travelling birds, apparently have a good margin of safety in their cardiac mechanism.

Analysis of the associated pathology will reveal that among the mammals, renal disease, chronic infections and diseases of the thoracic serosa are most often responsible for hypertrophy, and that something over one-third of the hearts showed myocardial damage. Among the Aves arteriosclerosis and renal disease are most important in enlarging the heart; half of the cases had myocarditis. In so far as dilatation in mammals is concerned, renal disease and acute infections are decidedly more important than other influences, even than the next in order—chronic infections and pulmonary diseases; only one-fifth of the cases had myocardial disease. Acute infectious disease is the most potent cause of dilatation in birds; only two of the eight cases had degeneration of the heart muscle.

If a comparison of the incidence of increased muscle bulk in the two classes be made^[9] it will be found to occur two and one-half times more often in mammals, 60while dilatation occurs nearly ten times more often among the mammals than among the birds. Hypertrophy is accompanied by myocardial change in 44 per cent. of the cases, whereas muscular degeneration was only seen in 24 per cent. of the dilatations; this change is conspicuously lacking in the Primates, Ungulates and Marsupials. The usual teaching has been that dilatation, which means enlargement of chambers and thinning of walls or at least no thickening thereof, implied an inability on the part of the heart to keep up with increased demand—a decompensation. If Starling be correct that dilatation is not a degeneration of pump value but merely one of adaptations to increased demand, then this method is more characteristic of mammals than of birds. There is, however, the reserve power to increase the muscle bulk inherent in the mammalian, not possessed or needed by the avian heart. The large-hearted class Aves certainly dilate their blood pump less frequently than mammals and indeed have less cardiac disease.

An analysis of the incidence of hypertrophy versus dilatation shows that hypertrophying power resides in the Primates, Accipitres and Struthiones, their hearts relatively seldom dilatating. Lack of such power and consequent dilatation resides in Rodentia, Ungulata, Marsupialia and Anseres. Hypertrophying power lies therefore chiefly in the heart of average size for its class, dilatation occurring in the small heart. (See page 63.)

There is little to be learned from the nature and anatomy of the hypertrophies and dilatations except perhaps their character among the birds, in which the physics of the circulation is somewhat peculiar. In this class both the hypertrophy and distention are predominatingly left-sided, a state probably explained by the pressure against which the pump must work in flight because then the lungs and the viscera are somewhat 61compressed by the pressure of an excess of air in the pneumatic sacs. At all events while concentric hypertrophy was mentioned once, it is difficult to estimate the degree of increase in the right chambers because they are not uncommonly well filled when diastole occurs at death. Grober^[10] asserts that the normally large heart (or what I have called “physiological hyperplasia”) shows a “hypertrophy” of the right ventricle because of the extra work entailed in flying. This is certainly not the case in the material we have seen under pathological conditions. Right sided increase might be expected if pulmonary or serous membrane affections were prominent, but left-sided increase, following arteriosclerosis and nephritis is the actual finding. The best examples of concentric hypertrophy are in the dogs with thyroid disease and the best examples of concentric dilatation in ungulates suffering shock.

The foregoing pathological data can now be summarized by grouping the facts under the headings of absolute and relative vulnerability of the heart. By the former is meant the actual number and quality of lesions in the various orders, but here at once one comes upon the irregularity of examples of zoological and pathological character, and if one trust entirely to the percentages, fallacious conclusions might be reached. Basing judgment upon the incidence of pathological lesions in mammals and birds, it is evident that the former has greater vulnerability, as 13 is to 6.2. This is noteworthy as we shall learn that the bird has a larger and apparently better prepared heart than the mammal. Attempts to discover the order or kind of animal having the greatest or lowest vulnerability are difficult for the reason given above. Thus, for instance, Pinnipedia, Proboscidea, Edentata, Gaviæ, Impennes, Steganopodes, and 62Struthiones present the highest percentages of cardiac lesions, but the total specimens examined are so few that these figures may well be misleading. (See Tables 1 and 2.) If, however, figures mean anything in such small groups, these are the animals which have the greatest cardiac vulnerability. They have little in common in regard to zoological relationships and habits; four of the seven orders are rather slothful and three are active. It is much better to limit our observations to those orders from which sufficient examples have been subjected to autopsy and upon which we have some standards for comparison in the heart-body weight ratio. It so happens that in the above seven orders I was unable to obtain any reliable figures of heart weight. Table 3 is a combination of data from Tables 1 and 2 for the principal orders from which we have enough material (at least one hundred autopsies) and for which it is possible to obtain as comparative standards figures indicating the weight of the normal heart in kilograms of body weight; Table 4 gives these ratios for normal hearts. The information about the weights was obtained from some of our own figures and the references given in the footnote.^[11] There are no extensive data upon weights and measures in exact terms, such as body weight, so that we are limited to the numbers quoted in parentheses besides the orders in the table. The ratios might be modified slightly by a greater number of examples, but they show certain things by comparison of the classes; in a rough manner the heart ratios correspond to the pathology.

However, there are many reasons why great caution should be used in evaluating the relative size of the heart. Welcher showed in his work that the proportion is 64greater in small and young animals than in large and adult ones. All the authors quoted agree that in birds and to less degree but still clearly in mammals, there is a direct relationship between the bodily activity of an animal and its cardiac bulk. This is fairly well shown in the list of avian heart ratios, but not so clearly in the mammals. What shall be considered the most active mammals—the monkey, perhaps, with his tendency to be occupied constantly, yet we find the greatest heart bulk among the Carnivora, animals prepared for travel and struggle, and the smallest among the Rodentia, quiet and timid animals. The avian order showing the greatest cardiac ratio, the Fulicariæ, shore birds, is made up of some quiet hiding varieties, and of some capable of very prolonged flight; the most constantly active fliers (Passeres) also have a high cardiac weight proportion. The inactive owls have the smallest heart bulk.

The contrast between the average heart-to-body weights of mammals and birds is striking, the latter having two and one-half times as much as the former, 5.8 vs. 13.8. Since this is the most prominent and best supported statement in the table of weights, it may be used to compare with the incidence of the pathology as seen in the two classes.

Degenerations and inflammations occur in mammals and birds as 9.5 is to 5.5.^[13]

Hypertrophies occur in mammals and birds as 10.3 is to 4.3.^[13]

Dilatations occur in mammals and birds as 2.4 is to .28.^[13]

In other words, mammals are much more susceptible than birds to degenerative and inflammatory processes, show an ability to increase the muscle bulk two and a half times as great and are liable to chamber distention nearly ten times as often. It might also be put 65that birds cannot or do not need to increase their muscle, and that the chamber and muscle balance is more perfectly arranged.

While in the preceding pages hypertrophy has been discussed rather from the standpoint of its value as a compensating and reserve capacity, and dilatation as a degenerative or decompensatory process on the part of the cardiac mechanism, it may be that dilatation of the mammalian heart is the usual method employed by the class in response to increased demand. It seems certain, however, that the originally and normally larger heart, both mammalian and avian, more often uses an increase of its muscle to this purpose.

Hypertrophy was accompanied by myocardial disease in 44 per cent. of the cases, while dilatation showed this change in only 24 per cent. This supports the theory that dilatation is a normal response of the myocardium under strain and the belief held in many quarters that the muscle increases its bulk because some of it is damaged.

The differences between classes are not so conspicuous between orders. However, the large heart of the carnivores increases both its muscle and chambers, while the small heart of the rodents and marsupials more often dilates. Analysis of the avian orders is inconclusive and somewhat contradictory. Let it suffice to say that the birds which fly most, with exception of the ducks, have a relatively low vulnerability, and the soaring carnivorous Accipitres and the largest birds, Struthiones, apparently have a high susceptibility to damaging influences and enlarge their muscle bulk in response to increased work.

Aneurysms of the heart are quite rare; only two have been seen. They were both located at the apex of the left ventricle in birds; they did not rupture. Myocardial damage is evident in both cases but the cause is not clear; parasites could not be demonstrated. Plimmer reports a case of cardiac aneurysm at the apex from infestation of the heart muscle by sarcosporidia.

SECTION III DISEASES OF THE BLOOD VESSELS — Thromboses. — Arteritis. — Degenerative Arteritis or Arteriosclerosis. — Summary on Arteriosclerosis. — Aneurysms.

The gross anatomy of the blood vascular system is constructed upon the same general scheme throughout mammals and upon a comparable basis in birds. Microscopically there is little variation throughout the orders unless it be in the relative proportion of muscular and connective tissues. The origin of the great vessels at their cardiac base and their distribution to the pulmonary and to the greater circulations in no way differ in these two classes in that it always consists of an efferent pathway to the lung and a root vessel above the aortic orifice. The former has usually quite a distinct origin on the right side, but in some birds the posterior wall of the pulmonary artery may overlie the entire aortic base; this, however, is not the rule for birds. The aorta in most mammals remains a separate and distinct vessel for some distance, after which it gives off the innominate and subclavians. In the birds on the other hand, the stretch immediately above the aortic valve is usually ballooned out somewhat, into a sort of sac or ampulla from which the subclavians and descending aorta arise. This forms a structure of rather trident shape, the lateral prongs being the subclavians, the middle and posterior being the aorta proper. In some birds the aorta may have the length of a centimetre or more then dividing into the left subclavian and right aorta from which the right subclavian comes off.

There is definitely more support to the heart and vascular roots in mammals than in birds, in the latter class these structures lying quite free between the lateral air sacs and well in front of the lungs. Nor is there the richness of mediastinal areolar and fatty tissue in the winged creatures.

67The vessels of mammalia retain a considerable wall throughout nearly their entire length. At first the wall is thin compared to the calibre of the vessel while the arteries smaller in calibre, have a heavy wall. In birds the arterial stalk at the heart is supplied with very heavy walls, but after the second branching the relation of wall to calibre seems to continue about the same. In this class the stalk vessels have wall to calibre relation of 1 to 3 (measurements in 2 Passeres, 1 Psittaci, 1 Accipitres) whereas in mammals the relation varies from 1 to 5 to 1 to 7 (observations on 2 carnivores, 1 ungulate, 2 rodents). In mammals the consistency of a normal artery wall remains much the same, a firm, resilient, yellow-white tissue, quite opaque and standing open upon cross section. In birds this description covers the main stalk, the aorta in the abdomen and the first part of the carotid and iliacs. When these characters are lost, the arteries become semitranslucent bluish strands so that they are difficult to follow in the muscles of the neck and extremities. This is particularly true in the Passeres, Picariæ, Galli and Columbæ while in the Psittaci, Accipitres, and Anseres the arteries are distinctly whiter than the veins but yet quite soft. In the Herodiones and Struthiones, thick walled vessels may be followed as far as the second joint in both extremities. These differences depend in part upon the grosser construction of the central arteries in Aves and in part upon the larger amount of elastic tissue in them than in the secondaries and smaller vessels, and than in comparable mammalian vessels.

It is impracticable to go into the minutiæ of histology in the different orders, which indeed varies but little, although attention might be directed to the facts that in all central vessels the relative amount of elastica is greater than in smaller ones and that muscular tissue seems to exceed in the latter. Considerable work has been done upon the amount and arrangement of muscle bands in isolated genera, but no comprehensive data are at hand 68upon orders. The strands of muscle do not seem arranged so regularly as in mammals; the pulmonary artery of the cat, for example, has a muscle arranged like an oblique band in waves or festoons along the length. The mammals as a class seem more richly supplied with arteries and veins than do the birds, and the square area of the vascular system is likewise larger. This is distinctly different from the amount of heart bulk as given in the discussion of kilogram-heart ratios so that one might say that the birds are “overhearted and undervesseled.”

In so far as the physiology of the two classes is concerned it is obvious that a different regulatory system is necessary because, aside from the variations of pressure incidental to pulmonary, muscular and visceral work, there remains the altering pressure within the air sacs of Aves, a force different under states of rest, of running, of deep water swimming and of flying with or against the wind. Part of the internal air pressure variation is cared for by the ability a bird has to respire the air in its sacs and bones, but in prolonged exposure to the pressure under water or during protracted flight some compensatory mechanism doubtless exists. This seems to reside in part in the heavy elastic quality of the arterial stalk and the very rich venous supply of the abdomen, including the renal-portal system and the distensible pelvic veins. Just where the governing power for this mechanism resides is as much a matter of debate as in the case of the human being, but certain researches would place it in the caudate lobe and pituitary body.

Having discussed these general comparative data we can now pass to a consideration of the pathology seen at this Garden. The subject will be studied from the standpoint of the vessels as a system and the changes peculiar to it. Naturally the most important lesions affect the great stalks and the principal trunks, from which the processes may continue into the smaller vessels. The 69essential alterations are inflammatory and degenerative, of which the latter are by all odds the more important. The former are either involvements of the vessel walls by frankly infectious processes, or less easily proved to be bacterial in origin, as is the case with periarteritis nodosa. Acute arteritis and phlebitis are constantly encountered and present nothing unusual. General nodal periarteritis has been seen in the lower animals, Lupke having reported^[14] before the German Pathological Society a big outbreak in cows, but it is less common than among men; we have not discovered it here.

Thrombosis is practically always a parasitic or an infectious process although at times considerable difficulty is encountered in explaining the source of the worms or bacteria. Thus, for example, the iliac or femoral thromboses which are at the bottom of intermittent claudication, are frequently quite vague in origin. We have had one such case in a deer in which a partly occluding thrombangeitis existed in both femoral arteries and veins. Mesenteric thrombosis, a serious condition in cattle and horses from infestation with sclerostomum or strongylus, has not been proven at the Garden, but we have seen one case of numerous thromboses of the venous radicals in the jejunal wall apparently due to some nematode larvæ; the specimens were so soft by decomposition that determination was not attempted. There occurred a thrombosis of the cava and aorta originating from a necrotizing cloacitis, apparently streptococcal in nature, in a Demoiselle crane. The clot, while not totally occlusive, extended nearly as far as the heart in the vein and the abdominal aorta. There is also on record a thrombosis of the vena cava and right pulmonary vein in an American beaver, harboring Hepaticola hepatica in the liver, with a fibrosing pneumonia due to this parasite. 70Another case in which parasites seemed to take a hand concerned a common raccoon with tapeworms (sp.?) in the small intestine and microscopically discoverable parasitic parts in the lungs; these organs were the seat of extensive congestion and venous thrombosis, the latter containing really enormous numbers of diplococci. The parasites probably paved the way for bacterial invasion. A frank case of septic thrombotic aortitis was noted in a Rice Grackle, the infectious focus apparently being a vegetative “tricuspid” valvulitis.

In addition to these cases, productive inflammatory changes were discovered five times affecting vessels in or near frank inflammatory processes. The animals affected with this productive process were three birds, a rodent and an elephant. In the case of two birds and the rodent the process was associated with chronic intestinal lesions, while in the elephant it was found as an endarteritis obliterans in large vessels of the lung of chronic pulmonary tuberculosis occurring in this animal. These instances serve as examples of the truly productive inflammatory processes affecting vessels and illustrate the distribution through the animal kingdom. Pathogenetically there are no essential differences, and histologically they correspond to the forms seen in man. Had every piece of tissue been subjected to microscopy wherein such lesions might have existed, more examples might have been discovered, but these processes excite no peculiar secondary effects so that attention is not drawn to them directly. The only noteworthy difference between mammals and birds is the fragile character of the clots in the latter class. This is peculiar because the principal response of this class to an infectious irritant is coagulation necrosis, liquefying enzymes apparently being absent or small in quantity.

71Fatty deposits in the aortic intima are by no means uncommon in the human subject and are encountered at all ages, even in youth at a time when progressive arteriosclerosis does not accompany them. There is a belief in many quarters that this fat may be laid down and then removed. Such deposits are exceedingly rare in wild animals; when they occur it is in small indefinite patches and not the bands or rows as found in man.

Whether or not it be exact to speak of the more protracted forms of vascular disease usually called arteriosclerosis or atheroma as degenerative, such changes form the most pronounced features of the lesions, and 72we have made such a separation at this laboratory. Here is not the place to engage in the academic discussion of the nature of the process, but I wish to state that collectively the changes as seen in such lesions in the lower animals are more degenerative than productive, and that we have never seen true ulcerative atheroma as it not uncommonly appears at the autopsy table in any large hospital. This disease of the vascular walls has long been attributed to alcohol, gout, syphilis and other such prolonged intoxications to which we might apply the light term of “toxins of civilizations.” Too little credit, or discredit has been given to chronic intestinal disorders, overeating, and overdrinking of ordinary fluids, to entirely incorrect diets, and to chronic bacterial diseases. Even though the exact counterpart of the disease in man does not occur in lower animals, we shall see the probable association with food and with habits, in a manner discordant with former teaching of the causation of the disease.

The group to which the name degenerative arteritis has been applied is, as has already been indicated, more productive than the analogues seen in the human being, but indeed it is questionable whether the lesions even in the lower animals are not more degenerative than productive. Since, however, chronic arteritis is always associated with damage to the elastic and muscular fibres of the media as well as with fatty change and overgrowth of the intima, all the deforming and degenerative cases will be classed together.

The general picture in mammals is one of diffuse rather than of plaque-like thickening, but well outlined raised or depressed areas are encountered. In the aorta and larger branches one may find irregular streaking and loss of elasticity with fairly clear, pale yellow or gray, flat sections of distinct opacity. Rarely these may contain calcareous matter, a change most often seen in the carnivores. The lesions are very largely limited to the aorta; 26 or 76 per cent. of the 35 cases had this distribution alone. The arch seemed never to be affected alone, and indeed it is rather commoner to find opaque patches stretching along the thoracic or even abdominal portion; this is especially true of the Ungulata.

Fig. 2.—ARTERIOSCLEROSIS AND ATHEROMA. THORACIC AORTA. JACKAL (CANIS AUREUS). THIS WAS CONTINUED TO THE MESENTERIC AND ILIAC VESSELS.

73There have been also in mammals five cases of mesial change which have given rise to the picture described by Mönckeberg and usually entitled by his name. However, the noteworthy differences between the wild animal and the human cases are the absence of advanced calcification in the media under the concavities and the prominence of the changes in the aorta near the heart to be found in the former. These few cases do not permit an association of the arterial disease with any particular pathology in other parts.

Considered minutely, the outstanding lesion in the class Mammalia is the separation of the elastic fibres by fluid and debris, apparently derived from the degenerated muscle fibres, associated with a decrease of round and elliptical nuclei. Globules and hyaline pink staining material are often collected between split-up elastic strands, which fibres in some cases seem quite numerous, in others reduced. In the intima heaping-up of cells and fibres is very moderate in degree while usually one finds only subendothelial edema. When the process has advanced far, the microscopy is like that of well developed human lesions. Arterial degeneration due to parasites gives a different picture in that medial degeneration is far advanced and some fibrinocellular activity is seen upon the intima when this tissue remains. When, however, the infestation has proceeded to weaken the wall sufficient for it to give way into an aneurysm, little or no vestige of the true arterial wall is left.

In the Aves the distribution and anatomy of this process present some differences. The aorta is as usual most conspicuously the seat of change, but it is noteworthy that the dilatation or ampulla immediately above 74the aortic valves and from which the main vessels spring, is practically always free of lesions which are on the other hand most marked in the thoracic and abdominal sections. One’s attention is usually attracted to the aortic surface by its roughness although visibly there may be no plaques, but upon close inspection a mottled opacity may be detected. This all seems due in the few cases subjected to tissue section, to hyperplasia of endothelia, with or without fibre increase. The media may show muscular granularity or no change at all. At the stage when plaques are formed, fairly well outlined, firm but rather brittle, raised areas are detected, seated upon a distinctly opaque gray wall. The remainder of the vessel may be smooth and elastic but sometimes, in the Accipitres for instance, a general resistance to pressure and tension is found. Microscopically such a vessel will show a media the seat of ruptured muscle fibres, split-up or broken elastica and some debris, while the intima is covered with active and distinct fibrocellular exudate.

I have for comparison divided the cases into those in which the superficial productive character was prominent and those seemingly entirely a degeneration of the media, that is with inactive intima. In mammals 77 per cent. of the cases were of the degenerative type while in birds 50 per cent. were of this kind. The exact importance of this difference is not easy to evaluate, but with the facts that the bird has a greater elastic supply for its large vessels and a greater wall to calibre ratio, it is interesting. The aorta alone was affected in half of the birds, the remainder showing lesions in the carotids and femorals.

The tendency for the media to degenerate would lay the basis for concavities on the intimal surfaces after the type seen in Mönckeberg’s sclerosis. A number of cases of this variety have been encountered, but instead of being better developed in the vessels of extremities as in man they have presented more definite pictures in the aorta and pulmonary vessels. Examples will be quoted under the discussion of the various orders.

Fig. 3.—ARTERIOSCLEROSIS, ATHEROMA AND ANEURYSMAL DILATATIONS IN THORACIC AORTA. WILD CAT (FELIS RUFFUS).

75Primates are not often affected with degenerative arterial disease, two of the instances observed showing this change confined to the coronary vessels. As might be expected the myocardium in both was affected, and in one animal had a definite concentric hypertrophy. A very interesting case was encountered in a Lion-tailed Macaque (Macacus silensis). His heart showed distinct fibrosis of the conducting pathways from auricle to ventricle and of the papillary muscles. No atheroma was present in the aorta, but in the pulmonary distinct sacculations of the Mönckeberg type were found. Mesial degeneration was apparently responsible, but no calcification had occurred. Death was due to acute gastritis.

Carnivora present about half the cases seen in mammals and 16 per cent. of the total. Five of the sixteen cases owe their origin to parasitic arteritis and were combined with aneurysms. As will be noted by consultation of the list there is no outstanding accompanying pathology, a fact which makes parasites more important. One case of mesial degeneration, resembling the Mönckeberg type was observed in the thoracic aorta of a bear.

Ungulata are generously represented, thirteen cases being recorded distributed rather unevenly between the odd-toed (1 or 8.5 per cent.) and even-toed groups (12 or 2.9 per cent.). The single case in the first group occurred in a Zebra (Equus burchelli) wherein was found about the middle of the thoracic aorta a diffuse thickening of media and intima in a circular plaque approximately two centimetres in diameter; it was by no means so well developed as similar lesions in the even-toed ungulates. This recalls the expression of doubt by Zinserling as to the occurrence in the horse of arteriosclerosis similar to that in human beings.

76The lesions in the Artiodactyla are both in plaques and diffuse, the aorta and its branches sometimes being quite wrinkled but beset with firm elevations with and without calcification. These changes are fairly definite and, although they never attain the development seen in man, resemble the stage of wrinkling and roughness in the preulcerative stage of the human analogue. Two of the cases were associated with dilatations of the mesenteric vessels and with periarteritis, a picture strongly suggesting parasitic infestation; in one case ineffectual search was made, in the other no record is made of the parasites. Renal disease occurred only twice and myocardial damage only once. Chronic pulmonary disease, present thrice, took the form of tuberculosis twice and pleural adhesions with atelectasis once.

Marsupialia present three quite interesting cases, a Tasmanian Devil (Sarcophilus ursinus) and two Kangaroos (Macropus). The first showed distinct sacculations in the ascending aorta, suggestive of Mönckeberg’s sclerosis but equally resembling several small or incomplete aneurysms. The underlying vessel was opaque and stiff, continuing so to the middle of the thoracic portion. The other marsupials showed distinct mesial damage with early calcification and a roughened intima; once the pulmonary artery was involved.

It will be noticed that the orders Rodentia and Lemures are missing from those showing arterial disease although we have a reasonable number of autopsies upon them.

Passeres are hardly good exponents of vascular disease, an interesting thing in view of their large heart, heavy vessels, and flying habits. It is, however, striking that two of the three birds of this group had aneurysms of the aorta, one of which ruptured just above the origin, partly into and partly outside the pericardium. Despite several microscopical sections we were unable to find the tiny ends of the breach and any evidence of parasites. In the other case a vegetative growth occurred on the intima near the dilatation.

Fig. 4.—ARTERIOSCLEROSIS IN AORTA. OTTER (LUTRA CANADENSIS). THERE IS RELATIVELY LITTLE INTIMAL CHANGE, THE MEDIA BEING FIBROTIC AND ALLOWING THE INTIMA TO BE DEPRESSED IN SMALL CONCAVITIES.

77The Picariæ were represented by a Hornbill and a Toucan. The former presented roughened yellowish elevations for two centimetres above the aortic valve; this seemed the only involvement. The Toucan had a few small scattered but deep yellow plaques in the same location.

Psittaci, although failing to be accredited with a high percentage of arterial disease, nevertheless present some striking and interesting changes. In the first place, the central vessels are not so conspicuously the principal seat of atheroma as is the case in many other orders, and the lesions are not so productive. It is usual to find flat areas of opacity, perceptible as easily by section through the wall as by holding up the opened vessel to the light, the seat of the density being in the media. This can be followed into the wing arteries and, upon microscopic section, these smaller vessels will show mesial degeneration, thus being comparable to arteriocapillary fibrosis of man. However frequent this picture may be, there are also instances of overgrowth in the intima, prominences over opacities or raised plaques at the points of branching, lesions which correspond to the activity of the inner coat. It is interesting that renal disease, chronic pulmonary and general infections occur in a goodly proportion of these birds.

Striges is an order of little importance. The lesions in the two cases consisted of rather prominent plaques in aorta and large branches.

Accipitres stand out as giving the greatest percentage of any order of which we have had a fair number upon which to make comparisons. Their arterial lesions are frequently accompanied by renal, myocardial and valvular disease. Mesial and intimal alterations are about equal in degree, irregular patches going on to softening without ulceration, and early calcification being quite prominent. The sickle at the branching of the renals is a 78favorite site of deposit. Like the parrots their arterial damage is not confined to the aorta, but may be found in the carotids, femorals or small wing arteries. The most common situation is, however, in the lower thoracic and renal regions.

Galli, represented by five specimens, seem to have their vascular disease accompanied very often by myocardial and infectious disease. Their arterial pathology consists of raised gray patches in the aorta only.

Steganopodes give the highest percentage among avian orders, but this must be held sub judice because of the small number of specimens subjected to autopsy. Renal disease occurred in three cases. Their lesions are in the form of yellow opaque streakings in the aorta and its branches, in one case following the carotid half way up the neck. Plaques are not common, and when they occur are streaky and illy outlined.

Herodiones, represented only by a heron, are negligible. This bird showed a diffuse thickening with early thrombotic deposits attached to the intima.

Palamedes are represented by a Screamer which showed around the orifices of the renal arteries an early fatty deposit and mesial opacity.

Anseres present a considerable number of cases which are accompanied by cardiac, renal and general pathology. The character of the lesions is like that of the Accipitres and the distribution differs in only one particular. In four of these eleven cases the elevations or opaque areas were limited entirely to the stretch of aorta which might be compared to the arch in mammalia, that is the part with which the right subclavian is in closest contact and which bends almost directly backward to become the thoracic aorta. This excludes the ampulla just above the aortic valves. There seems no real reason for this and it may be accidental.

Fig. 5.—AORTIC ARTERIOSCLEROSIS. SARUS CRANE (GRUS ANTIGONE). THE LESIONS ARE ELEVATED AND IRREGULAR.

79Struthiones, with seven specimens having arterial disease in the great vessels alone, seem to have no especial characters unless these be in the heavy furrowing and stiffness of the wall, with opaque, elevated, indefinite patches, seen mostly in the descending aorta; once a long tough and partly brittle stretch was found in the carotid.

Alectorides, with a relatively high percentage, present irregularly outlined fatty and finely granular patches in the intima of the lower aorta and abdominal vessels, and, in two cases, as far as the vessels of the lower extremities could be followed.

The orders Columbæ and Fulicariæ are missing from the list of Aves having arterial disease, yet a reasonable number of autopsy records are at hand.

Having discussed the orders separately, a review of the whole situation is desirable. Chronic arteritis, or as it is usually called arteriosclerosis, is common to very many zoological orders, and its principal lesions are comparable throughout the two classes under consideration. A statement as to its incidence would best be made by adopting an arbitrary number of observations as the desired minimum upon which to draw conclusions, and I shall adopt one hundred as such a figure. Accepting this as reasonable, a review of the table indicates that the order of percentage incidence is: Accipitres 6.6, Ungulata 3.5, Anseres 3.4, Carnivora 3.3, Striges 2.2, Psittaci 1.8, Marsupialia 1.8, Galli 1.6, Primates 0.6, Passeres 0.22; the other orders have less than one hundred specimens each. There is no doubt that carnivorous birds have the highest incidence of chronic arterial disease. Next in order come three varieties with nearly equal incidence, the ungulates, anserine birds and carnivorous mammals. These orders have little in common unless it be that in nature they are often engaged in prolonged or strenuous effort, as in fight or flight. We possess no measurement of their vascular supply but by consultation of the table giving 80heart weights (page 63) it will be found that three of them have values below that of the class in which they belong; the Carnivora alone have a greater heart-to-body ratio than the average for its class Mammalia. Nor do these orders have any direct dietetic relationship. The expected longevity of these groups does not permit one to discover any reason for arterial changes except perhaps that they have a reasonably good viability under park conditions, and therefore many have a longer opportunity to develop vascular disease. It so happens, however, that the first four groups are the most likely to suffer from gastrointestinal inflammation, of dietetic or bacterial origin.

It is interesting, but not easily explicable that the orders of great activity, Primates and Passeres, are at the end of the list; their food is very largely carbohydrate in character. Just why Lemures, Rodentia and Columbæ should be missing is not quite clear, because orders of comparative habits and food are included.

A review of the concomitant pathology reveals the fact that nephritis more often accompanies these processes than any other single condition. Among the chronic infectious disease in the table is included chronic enteritis; this group falls well behind the renal diseases. The relatively small number of cases of valvulitis speaks rather against an active infectious origin of the vascular lesions.

Aneurysms have been observed all over the world and in nearly all the larger orders. The London Garden has had an unusually large number to report, the most striking being that described by Seligman in the 1906 Report of the Society, in a tiger thirteen years in captivity which had fourteen sacculations from pea to plum size scattered along the aorta. Even with the number of cases on record and those collected here it would be unwise to draw deductions as to their incidence or as to the possibilities of vascular dilatation in any given order. Horses have aneurysms occasionally, cows and dogs rarely, according to Rievel. I can, however, state that there has not occurred in our experience a large growing pulsating aneurysm in the aortic arch region comparable to the condition so well known in man. The literature to which we have had access gives a definite impression that parasitism of vessel walls is the most important factor in the causation of ectasia, and that simple non-parasitic arteriosclerosis is relatively unimportant. Two of our seven cases seem to have been free of parasites but the notes cannot entirely assure one of this. The distribution of cases at this Garden is found in Table 5.

Fig. 6.—PARASITIC ANEURYSM IN THORACIC AORTA. PARADOXURE (PARADOXURUS LEUCOMYSTAX). PARTLY SACCULAR, PARTLY DISSECTING ANEURYSM WITH OPEN THROMBOSIS AS INDICATED BY THE GLASS ROD. PIECES OF WORM FOUND IN WALL. COULD NOT OBTAIN WHOLE SPECIMEN, SPECIES UNDETERMINED.

81A dilatation of the first part of the arch in a seal to a size which might be described as an aneurysm caused us to make such a diagnosis, correctly enough from the size and shape of the vessel but possibly worthy of reconsideration in light of the fact that no damage to the wall was found. At the heart and in the descending arch the diameter measured 4–5 cm., while the first part of the aorta measured 7.5 cm. This great irregularity in width could not be found in other seals albeit this section of the arch is usually a trifle larger than its origin and descending portion. The cava in seals is also large, but in this particular animal it measured 6 cm. across at the liver where there is a normal dilatation. These two spaces are looked upon as normal reservoirs for blood during diving, but the case in question seemed to have excessive “aneurysmoid” enlargements without mural disease. London reports an aneurysm of the aorta in a seal.^[17]

Aneurysms are not so common in birds, the incidence being in comparison with mammals as 1 to 2.2. Two seats are prominent for their development: the sinuses above the aortic valves and the first part of the subclavian vessels; two of the six cases occupied the first position, two 82the second, while one other lay in the arch of the aorta, the last in its descending thoracic portion. Those developing over the valves seem to arise from simple degenerative arteritis; those that occupy the other locations are apt to be surrounded by plaques on the intima. Aneurysms in birds reveal by microscopy some trace of all the vascular coats and seem not to construct an adventitia from surrounding areolar tissue. The veins have presented no peculiar pathology, except in tumors which will be taken up later. A Derby’s Tyran showed a phlebitis and periphlebitis of the left subclavian vein, of mycotic nature, which led to death by rupture and hemorrhage.

SECTION IV DISEASES OF THE BLOOD AND BONE MARROW — Anemia. — Secondary Anemia. — In Mammalia. — In Aves. — Summary of Secondary Anemia. — Summary of Primary Anemias. — Leucemia. — Avian Leucemia. — The Bone Marrow. — Myeloma.

The production and physiology of the circulating blood seem closely similar in the two classes under consideration, although the anatomy is not the same in birds and mammals, variations also occurring within the latter group. Pathological responses follow comparable lines in that hemolyzing agencies, be they hemosporidia, absorptions from metazoan parasites or bacterial toxins, produce a reaction in erythropoietic centres, and positively chemotactic viruses call forth increases in the colorless elements. We have also observed a decrease of leucocytes in an Orang Utan suffering from influenza, a finding analogous to that in the human attack. There is, however, a much less ready response on the part of birds to any leucocyte-stimulating influence, in this class the mononuclears seeming to bear much of the burden assumed by the myeloid cells of Mammalia or at least appearing on the stage very quickly so that any increase of the latter is overshadowed by them. Perhaps this apparent difference may be further explained by the greater number of colorless blood cells, structures which might be called the principal secondary defences of the body and constantly at the disposal of the organism, normally present in the birds’ blood; they amount to 25,000 per cubic millimetre in birds, while in the mammals very few varieties have half this number. On the accompanying Table (6) will be found a few differential leucocyte counts now known to us.

87It would seem, from a general observation of simple and infected wounds and from a few blood counts, that the response of leucocytes in the lower animals is greater than in monkeys and man. The ease with which animals endure a wound and the rapid local pus formation about an infection speak for an easy mobilization of their cellular defenders; their connective tissue elements seem equally well brought into play. In so far as birds are concerned perhaps the normally large number of leucocytes and the participation of local tissue cells in response to irritation is a preparatory protective mechanism because of their relatively small amount of bone marrow which may not be able to mobilize new cells rapidly; many of the birds, notably those prepared for long flight, have much of their osseous system given over to air space. The number of red blood cells is also greater in Mammalia, which show a variation from 4,000,000 per cubic millimetre in some small genera to 12,000,000 per cubic millimetre in some ungulates, while birds vary from 2–5,000,000 per cubic millimetre. Despite these fundamental differences in the classes, pathological changes of anemia, leucocytosis and leucemia are comparable; polycythemia in lower animals is unknown to me but may of course occur.

As in human pathology this condition may be divided into the group that follows some disease which damages the red blood cells or their source, called secondary, and those cases not preceded by such a condition, called primary. Formerly this latter group, known as progressive pernicious anemia, was copiously represented, but study has discovered that worms, inorganic poisons and infections can produce a picture of grave anemia so that the formerly large group has dwindled. We now conceive a primary anemia to be one without discoverable responsible antecedent pathology, therefore a disease of the bone marrow itself. There is one variety, hemolytic anemia, which seems to be an intoxication of the bone marrow with solution of red cells, but the affected tissue puts up some struggle against the poison. In another primary, the so-called aplastic anemia, no 88activity at all is shown by the marrow, no young cells appearing in the circulation. Clorosis, or green sickness of young persons, is a primary anemia and presents itself as a moderate cell reduction with a disproportionately low hemoglobin percentage. As a disease entity this does not occur in the lower animals, so far as I am aware, but a very few hemoglobin estimations and a reference to the literature would indicate that well marked hemoglobin anemia does occur.

In so far as the pathology of anemia is concerned we are obliged usually to judge by the appearance of the blood and tissues, the yellowish pallor of the mucous membranes, the condition of the marrow and the amount of pigment; severe rapid cases show hemorrhages and prolonged cases have fatty degeneration of the parenchymatous organs. For a decision of the primary or secondary nature we must judge the accompanying pathology and the condition of the bone marrow.

Secondary anemia can be laid in general to insanitary housing or inappropriate diet over a long period, to chronic bacterial infection of low grade, to the action of blood parasites or those of the bowel which either suck blood or elaborate an absorbable toxin, or to single great or repeated small hemorrhages. We shall now consider the cases at the Garden. Perhaps many other animals have had a substandard blood, but these are the cases in which the gross appearance attracted close scrutiny in this direction. London has had much anemia, probably from their reported heavy infestation with parasites, but this factor has with us apparently played a small rôle in the production of anemia.

In so far as the Primates are concerned the one outstanding cause of anemia is degenerative disease of the osseous system. In both rickets and osteomalacia there 89is an irregular hyperplasia of the marrow, which is usually more marked in the latter. In osteomalacia one finds irregular areas of congestion or even hemorrhage besides masses of a gelatinous fatty tissue while scattered about are pink spots where the marrow is better preserved. In rickets, on the other hand, the tissue is more uniformly congested and less sharply separated from the endosteal osseoid material or the irregular epiphyseal spongiosa. The fibroid or osteoid growth of osteomalacia seems to be fairly well differentiated from the marrow tissue although it may send strands into the canal and across the spongy area. Histologically there is not a distinct difference in the appearances nor do they differ from the human analogue. In those cases which develop late in life the red cell centres are very few in number but usually active. In the blood, one finds a few nucleated and stippled cells, but not much change in size and shape of the erythrocytes.

It does not seem that the anemia can be the cause of death, for among our thirty-nine cases of osteomalacia and rickets, the prosectors have thought it of sufficient importance to record in the diagnoses but eleven times. There are usually complications of pneumonitis or enteritis to finish the animal before the poverty of the blood will do so, and our records show only a Black Spider Monkey (Ateles ater), a Silky Marmoset (Leontocebus rosalia) and a macaque (sp.?) with osteomalacia and grave secondary anemia. It would seem, however, that hemoglobin anemia must exist, for, despite one record of 40 per cent., Fleischl, no excess of pigment deposit is noted in the spleen, liver or marrow.

Carnivora have shown a moderate number of diseases of the skeleton but the occurrence of a marrow involvement seems less frank, although the anatomical changes are similar. However, there are three grave secondary anemias recorded in eleven carnivores suffering from osteomalacia and rickets. Another prime cause of low 90blood value in this order is gastrointestinal inflammation; in seventeen cases of anemia, of secondary nature, five showed gastroenteritis of severe grade or protracted character. Perhaps the most prolific single cause of this blood change is parasitism, six of the seventeen cases showing infestation, five of which are nematodes and two cestodes, one showing both. The details of these are worth recording. Two young Jungle Kittens (Felis chaus) from the same litter died of enteritis with a noticeable anemia; they harbored in their upper small intestine ascarids, and one of them had a few hookworms (sp.?). A Kinkajou (Potos caudivolvulvus) died from a general mild infection, emanating from a pneumonia perhaps, and showed a heavy infestation with tænia (sp.?). An American Wild Cat (Felis ruffus) died from acute catarrhal enteritis and anemia; the parasitological findings included Filaria fasciata, adults in abdominal and gluteal muscles, larvæ in the blood; Dibothriocephalis felis, Ascaris mystax and Uncinaria canina in the small intestines. While the blood was thin and pale and some pigmentation existed, the condition could not be called a picture of grave anemia. A noteworthy finding was the deep pigmentation of almost the entire intestinal wall. Ascaris mystax was found in an under-sized inbred gray wolf, killed because of poor coat; there was a marked anemia and atrophy of the skin. An Ocelot (Felis chibigonazon) gave a picture of anemia due to uncinariasis, but is not so instructive as the following. A Swift Fox (Canis velox) exhibited clearly a case of progressive secondary anemia from uncinaria, and the history is worthy of a brief recital.

Muscles atrophic, greenish black over abdomen. Fat absent. Lung is blotched by darker red markings where parenchyma contains distinct excess of frothy pink watery fluid. No fluid or adhesions in pericardium. Heart is contracted, and muscle is pale yellow and firm. The only abnormality consists of slight yellowing of musculature. The abdomen shows great omentum firmly adherent to fundus of bladder. No fluid or other adhesions in abdomen. The liver is normal in size, smooth in 91surface and has sharp edges, is friable and bright orange yellow. The section surface is glistening, smooth and dry. Organ is poor in blood content, greasy and breaks easily. Bladder is large, contents fluid green bile; duct patulous. Spleen normal. Kidney is small and smooth, diminished in bulk, normal location, smooth surface, and pale yellowish gray, consistency, soft, flabby. Ureters normal. Mouth and teeth normal. Stomach contains scanty brown fluid. Duodenum—Mucosa bile-stained, contained a solitary nematode worm. In its lower portion it becomes filled with a blackish red fluid, and its mucosa becomes studded by heavily outlined punctate hemorrhages whose positions are best seen through serosa. Jejunum similar in condition to duodenum and contains four small nematode worms. At one point, i.e., where the worm is located at beginning of ileum the blood staining of mucosa is strictly in neighborhood of the worm. Capillaries nowhere congested. Ileum contains slight amount of brownish black material, mucosa normal. Large intestine and rectum normal. Pancreas normal. Lymphatics normal. This is a case of death by anemia as result of bites of hookworms. There were certainly more than four worms present antemortem since no males were found, and this may be explained by a possible diarrhœa which has flushed them out. This idea is borne out by empty condition of gastrointestinal tract. Animal Parasites—Uncinaria canina. The four small nematode worms above mentioned conform in all respects to the given anatomical points of uncinaria. All four specimens are perfectly formed females. The location of the hooks was easily determined and established as being in the most dorsal portion of buccal cavity, and as projecting forward and ventrally in two groups of three each in same manner as described heretofore in similar infestations in foxes. The large nematode worm found in duodenum is, from its possession of three lips and its general form, an ascaris. The mustache, however, which is so commonly seen in ascaris worms from this region is absent. Postmortem blood of heart shows red cells granulated and almost worthless for histological study. Nucleated reds, however, are absent but other points valuable in settling the question of anemia cannot be determined.

Lung.—There are no abnormalities in supporting tissue. Alveolar walls are markedly congested. Bronchi normal and show no trace of larval hookworm infestation. Air sacs contain many red blood cells together with a few heart-failure-cells. Congestion of lung.

Liver.—No excess of fibrous tissue. Finer details of structure cannot be made out owing to advanced autolytic changes. The only possible pathological changes consist of localized areas where liver cells have fused to form notable masses of pink granular material suggesting local necroses. Autolysis.

Intestines.—Four sections are present and all show essentially the same character of changes. Interstitial tissue between muscular tissue and submucosa loosely arranged as though separated by edema.

On luminal side of muscular mucosa is a distinct zone of striking tawny yellow color with hematoxylon-eosin combination. This zone is 92smooth homogeneous and contains a few spindle and stellate cells with no capillaries and with little or no fibrillation. It abuts upon the fundi of the crypts. Interstitial tissue of mucosa is loose and infiltrated with round and spindle cells in its deeper portions. Here it is also congested but congestion is most marked toward lumen where masses of free blood cells occur in interstitial tissue, within lumina of crypts and within lumen of intestine itself; no parasites or ova are found. Epithelium of crypts has granular cytoplasm; goblet cell formation frequently seen; cilia well preserved. Edema; Subacute catarrhal enteritis Hemorrhage.

Six instances of nephritis, four parenchymatous and two diffuse, are recorded in the total of seventeen cases of secondary anemia in carnivores. Except in the skeletal disease the marrow is very mildly affected, some edema and reddening grossly and moderate hyperplasia minutely, being the only noteworthy changes.

The next order is that of the Ungulata wherein we have found but two cases of frank anemia, an Isabelline Gazelle (Gazella isabella) and an Aoudad (Ovis tragelaphus). The former had several lesions of different etiology and nature so that an impoverishment of the blood is not astonishing: parasitic (?) cyst in lung, chronic infective arthritis, calcareous tuberculosis, congestion and edema of lungs, osteomalacia, and osteofibroma of maxilla. The condition of the aoudad was too indefinite to permit conclusions.

The marsupials are represented by two common Opossums (Didelphys virginiana) and a Rufous Rat Kangaroo (Aepyprymnus rufescens), two of which suffered also from rickets. The condition of the bone marrow was unfortunately not recorded, but in other rachitic marsupials this tissue follows the changes seen in other orders. One opossum had a hypertrophic gastritis with numerous Physaloptera turgida, a worm frequently associated with chronic thickening of the mucosa; there was also an early portal hepatic cirrhosis with enlargement of the spleen.

93Among the Rodentia we have had anemias in a Beechy’s Gopher (Citellus grammurus beecheyi) and a Southern (Sciurus niger niger) and Western Fox Squirrel (Sciurus rufiventer). The first had a myeloma also, and will be discussed later. One of the squirrels had osteomalacia, while the other suffered with diarrhœa and showed hydropic degeneration of the kidneys, conditions probably due to acute intoxication.

The class Aves is represented by the orders Passeres, Psittaci, Columbæ, Herodiones, Gaviæ, Picariæ, Striges, Galli and Accipitres; the first four are well represented, but in the other orders only one or two cases have occurred. The causes of anemia in birds are essentially those discussed for mammals with the provision that greater attention must be paid to parasites, particularly those of the blood. Several slightly varying protozoa inhabit the blood corpuscles of birds, and numerous embryos may circulate after they escape from a parent lying in some organ or tissue. The rôle of blood parasites, intra- or extracorpuscular, in the cause of death or of anemia is, however, somewhat paradoxical. Plimmer seems to credit a heavy infestation with great value in the cause of death. In the human being an infestation of one cell in a hundred is a fair grade of malaria; such a relation is apparently common in birds, and we have repeatedly seen a much heavier seeding while Plimmer reports as many as 70 per cent. of the erythrocytes to be carriers of hemogregarines (he has seen 92 per cent. in reptiles). Can then the effect upon hemic function and vital resistance be great? It has been our practice to interpret the finding of circulating protozoa or of larval metazoa as merely reducing the resistance of the birds so that they succumb more readily to incorrect food, strange environment or infection.

94It is perhaps well to show the state of our records in the Passeres by a table.

In the first group, two of the birds showed cestodes, one a tænia, the other not examined for identification; three showed coiled filaria in the air sacs, two, tropidocerca in the proventricular wall and five had coiled filaria in the serosa of the stomach. The second group was infested five times with Halteridium and five times with embryo filariæ. Anemia was associated with gastrointestinal inflammation alone only once, the remaining five cases having other finding of greater significance. The three birds of the next group concerned one with tuberculosis, one with mycosis and one with a long continued abscess. It seemed worthwhile to separate four cases of anemia in which nephritis was a prominent association, in three indeed being the only other diagnosis. While it is impossible to state that either is dependent upon the other, and they may of course be coincidental, it is nevertheless noteworthy that such an obscure relation occurs here as well as in human pathology. In one of these birds seen recently there was in all probability a distinct hemoglobin anemia suggested by jaundice, pallor of the tissues, absence of pigmentations and the finding of large pale erythrocytes in the heart blood. The last group is a mixed one including some birds in which only anemia was diagnosed, others with prolonged hemorrhages, two tumors, intestinal sand, congestion of the lungs and the like.

The parrots and their relatives are represented by nine specimens, among which two had proventricular 95spiroptera, two had long standing tuberculosis and two had osteomalacia. The notes of the other three are not sufficient to warrant deductions.

Herodiones showed eight cases of anemia, five herons, one bittern and two storks. Parasites are noted in only three examples, herons, and it is noteworthy that these all had flukes in the proventricle or intestine; one also had ascarids in the proventricle. Two of this order suffered with long standing inflammation following bone injuries. Perhaps the outstanding features of this order are the erythrocytic picture and the condition of the spleen. The red blood cells seem very fragile or soft, for one often encounters in their fresh or stained preparation vacuoles or rifts in the protoplasm surrounding the nucleus. At first we thought these were hemosporidia, but repeated attempts at their coloration and the absence of pigment granules seem to warrant an assumption that they are artefacts. In five of the seven instances there is very definite evidence of present or past activity of the spleen. We have not always considered it sufficiently prominent to call it a splenitis, but follicular activity is commonly discoverable, and two cases of definite fibrosis are recorded. The sun bittern (Eurypyga helias) showed a chronic interstitial nephritis in the atrophic stage. No other of the wading birds showed secondary anemia. There are seven cases among the pigeons (Columbæ) where anemic tissues attracted our attention. Three were associated with osteomalacia, in one of which the marrow picture was that of an aplastic form being everywhere pale and flabby without cells under the microscope; it is further interesting in this case that there was a distinct but ineffectual attempt at bony regeneration by the periosteum. In another case, this time brought to death by an enteritis and cloudy swelling of the viscera, the marrow was hyperplastic and red, there being activity in the basic staining areas of the head and in the shafts. (Notes of the third case scanty.) None of the seven cases seems to 96have been associated with animal parasitism; one had tuberculosis. The other cases are obscure and not definitely connected with other pathology.

Ten more cases of anemia were scattered among seven orders. There is nothing striking or even individual about them worthy of special mention.

A review of our records shows that among 5365 animal autopsies we have recorded anemia of probable secondary character in 122 instances, 53 (2.8 per cent.) mammals and 69 (1.9 per cent.) birds. The orders represented, with the percentage for the order, are Primates, 25 or 5 per cent.; Carnivora, 18 or 3.7 per cent.; Ungulata, 3 or .8 per cent.; Marsupialia, 4 or 2.2 per cent.; Rodentia, 3 or 1.5 per cent.; Passeres, 37 or 2.7 per cent.; Psittaci, 9 or 1.3 per cent.; Herodiones, 8 or 8. per cent.; Columbæ, 7 or 4.7 per cent.; Picariæ, 2 or 2.3 per cent.; Striges, Galli, Gaviæ and Accipitres, each one case. A consideration of their associated pathology reveals the fact that four changes are prominently associated with secondary anemia, to wit: gastrointestinal inflammation, 26 times (15 mammals and 11 birds); parasitism, 29 times (7 mammals and 22 birds); osteomalacia, 24 times (18 mammals and 6 birds), and nephritis, 18 times (12 mammals and 6 birds); a few of these cases overlap, but this is rather the exception than the rule, and this does not militate against the importance of the connection with anemia. It will be noted that practically all the important orders of animals are represented, including species from all over the globe. There is, however, no especial relation of anemia to the kind of diet or digestive tract. Conclusions as to the meaning of these figures of incidence are hardly justifiable. In so far as the blood picture is concerned we can only record the qualitative appearance and the effect upon tissues. It cannot be stated that to external observation a secondary anemia 97presents any distinguishing features that a specimen in poor condition may not exhibit. The monkeys formerly dying of tuberculosis had not infrequently pale buccal mucosa and skin around the eyes, but upon examination of their viscera, blood or marrow the quality of their blood could not be called greatly substandard. Slide smears of secondary anemia in many specimens would occasionally show stippling or a moderate number of nucleated cells with anisocytosis and poikilocytosis. This is much more frankly exhibited in the Aves, wherein displaced karyolytic or pyknotic nuclei are very common. Mention has been made of the rifts in the protoplasm, seen in Herodiones, and this has been observed in other orders. Perhaps the most striking change is the increase of young erythrocytes and of thrombocytes in the winged creatures. The nucleus of the former reminds one of that of the human plasma cell.

The condition of the bone marrow corresponds with fair accuracy to that which one is accustomed to see in the human being. Certainly this holds good for the mammals, while among the birds, the few observations upon which we feel like relying indicate a nodular erythropoiesis of rather striking character. In the areas of reddening as seen grossly there will be found under the microscope an orderly arrangement of large red cells with loose chromatic nuclei about a very much larger cell of the same type, apparently the primary erythroblast. Outside of this group, red cells such as appear in the circulating fluid, are rather irregularly distributed in a marginal zone. I have seen small areas like this in apparently normal marrow, but the central grouping was not so large as in the anemic cases; it thus appears that we probably have the anatomy of erythropoiesis.

The deposition of pigment in the birds is in much coarser granules than among the mammals, in the former case large masses sometimes obscuring several liver cells 98or apparently blocking a lymphatic sinus; the Kupffer cells do not seem to be heavily laden.

The extramedullary formation of blood cells has been a matter of considerable interest and study in the human being, and as far as it concerns the circulating mononuclears, the general opinion seems to be that such a histogenesis exists. A decision in the negative is perhaps reached by the majority in the case of erythropoiesis, and as far as my observations go, this holds for all mammals. It seems worth while, however, to record an occasional finding in some birds, especially anemic ones, which may be of importance in their erythropoiesis. The adult red cell is a clearly formed ellipse with a distinct, deeply stained, sharply outlined nucleus of a shape corresponding to that of the whole cell. Young red cells have a more nearly circular outline but almost truly circular nucleus, the short diameter being at least proportionately greater than is the corresponding short diameter of the whole cell; this is also the nucleus whose internal structure resembles that of the human plasma cell. Groups of such cells have been seen in the interstices of the liver, sometimes as many as twelve, in a rather orderly formation. An excess seems at times visible in the spleen but not in orderly arrangement. Observations are under way toward determining the relation of this finding to the amount of marrow, the condition of the blood and the habits of the bird.

Primary Anemia.

As already specified primary anemia is apparently causeless, aside from the assumption that it is a disease of the marrow itself. Since there are only four cases, representing three orders and they cannot be grouped as could the secondary variety, the individual instances will be discussed separately.

Ring tailed Bassaris (Bassariscus astutus). Adult died after two weeks’ stay in the Garden with a history of general failure of condition. 99The diagnosis at autopsy was primary anemia, fatty degeneration of the liver, hemorrhages in intestines and spleen, hyperplastic bone marrow. The external appearance is of general good condition, fair skin, mucous membranes pale. Lungs collapsed, and gray-red. There are several small hemorrhages scattered irregularly throughout respiratory tissue. Lymph Nodes—small, soft mottled gray-red. Pericardium had slight excess clear fluid, and no adhesions. Heart normal in size, and of pale brown color. The liver of normal size, smooth surface and sharp edges, of a pale brown color, soft and friable. Has indistinct markings like yellow brown mottlings on section surface. gall-bladder contains some viscid brown bile. Spleen, normal or slightly less in size, consistency firm, capsule pale pearl gray, apparently not thickened. There are numerous small hemorrhagic spots on section surface. Interlying pulp is homogeneous deep red. Follicles not visible. Kidney, normal in size and shape. Trabeculæ faint. Capsule smooth, strips easily, smooth surface, and brown. Consistency soft. Medulla prominently striated, cortex homogeneous salmon pink. Stomach contains a little glistening mucus. Mucosa pale, flat yellowish, slightly opaque. There is a recent clot lying in some mucus just above pyloric valve. There is, however, no open vessel nearby. From pylorus to anus lumen contains some rather fresh smeared out or slightly clotted blood and mixed in with mucus. Mucosa is flat translucent, submucosa slightly injected in a mosaic fashion, otherwise gut wall is negative. No recognizable food present. Follicles not visible. Mesentery glands small, soft, pale yellow. Bones seem entirely normal. Marrow of long bones is firm, bloody. Marrow of ribs also deep red. Blood in intestinal tract is probably a recent slow oozing from intestinal walls, and was probably the last straw. Cause of this anemia could not be determined. Blood preparation not made because it was too long after death. Liver shows moderate fatty infiltration of marginal areas. Pigment is scarce, only a few granules being present in the Kupffer cells, not more than is often seen without marked anemia. There is a slight increase in interstitial nuclei but not in fibres. No obstruction or increase of bile ducts.

Kidney.—Very mild swelling of tubular epithelium but no exudative processes. Glomeruli show a few vacuoles but capsular space is negative to pigment. Bone marrow (Femur) fairly cellular in construction, but fat well mixed. Cellular areas well arranged, active, most of cells are small members of the larger mononuclear variety. Small lymphocytes abundantly represented. Most of the larger cells are non-granular, with centrally placed nucleus. Megakaryocytes fairly numerous, nuclei seem closely jammed into centre. No recognizable certain nucleated red blood cells, moderately number stippled cells, few adult red cells. Eosinophiles and basophiles quite few. Pigment small quantity.

This is a case of primary anemia of moderate severity and short duration, and probably of hemolytic character 100if one may judge by the bone marrow, although excessive pigmentation of the liver and kidneys was not found. Unfortunately the spleen was not minutely studied, nor was the central nervous system investigated. Atrophy of the intestinal tract did not exist.

Two cases occurred among the monkeys, but one example will answer, since the two were essentially the same.

The case to be cited was that of a Japanese Macaque (Macacus fuscatus). ♀ Young, weight three pounds two ounces, exhibited in the Garden about four months, and apparently in good shape until two weeks before death when it rapidly became emaciated.

Diagnosis.—Aplastic anemia, chronic atrophic gastritis. Atrophy of heart muscle, fibrosis of liver, slight local cloudy swelling of liver. Perilobular diffuse nephritis (subcapsular type). Congestion of spleen. Fibrillar fibrosis of spleen. Hemosiderin pigmentation of spleen. Local amyloid infiltration of spleen. Calcareous infiltration in medulla of adrenal.

Coat only fair, body emaciated. Pale muscles, fat scanty. Respiratory tract normal throughout save for slight emphysema. The Pericardium showed no fluid or adhesions. Epicardium glistening and slightly thickened. Heart pale in color. Abdomen shows no fluid or adhesions. Liver slightly decreased in bulk, smooth surface and sharp edges, hard, and rusty brown. Gall-bladder distended, contained green fluid. Spleen firm and normal in size. Capsule smooth, shape normal. Section surface, dark reddish brown, trabeculæ distinctly visible. Kidney, normal in shape, capsule smooth, strips easily, smooth surface, glistening, pinkish gray, consistency hard. Section surface, poor demarkation between cortex and medulla. R. Adrenal, thick orange yellow cortex, solid small brown medulla. Mouth and teeth normal. Stomach distended, contains gas and small quantity yellowish mucus. Mucosa everywhere normal. Postmortem blood examined, stained by Romanowsky, but red cells were disintegrated possibly by laking so examination is not satisfactory. Histological Sections: Heart shows normal epicardium quite free of fat. Myocardium peculiar in that fibres immediately under epicardium show marked broadening in a very narrow rather sharply indicated zone where nuclei are extremely large although not especially chromatic. Transverse markings here easily, although faintly recognized, have very indefinite borders, their longitudinal fibrillæ being ranged in form of a coarse reticulum. This comes about from frequent and extensive lateral anastomoses with fellow fibres giving appearance of a syncytium. In deeper parts, fibres are of more normal size but nuclei are still large and fibres, now cut in transverse section do not appear to anastomose so freely; there appears to be a slight excess of fibrous 101tissue in their deeper parts. Arteries quite normal. Atrophy with regeneration.

Liver.—Capsule and interstitial parts on whole normal. Perilobular fibrous tissues largely missing, but where remaining show an overgrowth occurring in peculiar zonal arrangement and of old adult almost hyaline type. Its fibres are often arranged strikingly in whorls. Bile ducts, arteries and veins quite normal. Parenchymal cells of normal size, finely granular, prominent normal nuclei and contain small quantities of finely granular, golden brown pigment not really as abundant as commonly seen in severe anemias. Blood capillaries narrow, contain small quantities R.B.C., and Kupffer’s cells very frequently contain fine granules like those of parenchymal cells but of a greener tint. In a few isolated areas parenchymal cells distinctly more swollen than others and many show disintegration of nucleus. Hemosiderin pigmentation. Perilobular fibrosis. Slight local cloudy swelling.

Kidney.—Capsule smooth, interstitial fibrous tissue of organ proper highly fibrosed in peripheral parts, but slightly in deeper. No lymphocytic infiltrations anywhere or sclerosis of vessels. Tubular epithelium highly atrophic in subcapsular regions where tubules are narrow. In deeper parts epithelium is at times so swollen as to occlude lumina, where they are coarsely granular and occasionally show some karyolysis, a pink hyaline or finely granular material. Tufts never show fibrosis, normal size. Bowman’s capsule heavily thickened. Chronic diffuse nephritis (subcapsular type).

Spleen.—Slightly hyalinized capsule, normal thickness. General reticulum of pulp slightly fibrosed and poor in lymphocytes. Sinuses broad, crowded with red blood cells, but only small numbers of lymphocytes. Coarse granular blood pigment abundant, showing greenish cast on focusing. Malpighian follicles normal size, slightly fibrosed, and in several instances show a deposit of smooth pink material between cells. Congestion. Fibrillar fibrosis. Hemosiderin pigmentation. Local amyloid infiltration.

Adrenal.—Organ appears normal in all respects save for presence of a few small irregular areas of calcification in medulla. These occur apart from any recognizable necrotic or fibrous areas. In one place one appears to lie within lumen of blood vessel. No fibroses or special congestions anywhere in organ, and cells show normal details and normal numbers of vacuoles. Calcareous infiltration of medulla.

Stomach.—Muscular tunic normal. Submucosa thin, has densely arranged bundles of smooth, pink character. Mucosa distinctly thinned, shows comparatively few regions holding acid cells, consisting for most part of peptic type of gland. These are short and of broader calibre towards lumen than deeper, suggesting a hyperplasia of luminal portions; stroma richly infiltrated with lymphocytes, not fibrosed or congested. Epithelium of crypts has rarefied appearance, shows no special degenerative changes. Chronic atrophic gastritis.

102Bone marrow appears as widely separated large, fat globules with intervening granular edematous material and no hematopoietic elements. Blood capillaries numerous and highly congested.

Although the notes fail to discuss the gross appearance of the bone marrow, the amount of alteration in its microscopy and the relatively small output of pigment in the liver, seem to substantiate the determination of aplastic anemia; it is unfortunate that the blood smears could not be used in the decision. At all events the condition of the intestinal tract, of the heart, liver, spleen, and adrenal, justify us in classing the case as one of primary anemia. The next and last instance is of the same type, although I am inclined now to differ from the diagnoses made at the autopsy table, that of aplastic anemia, and to place it in the hemolytic variety. The rapidity of the fatal attack, the redness of the marrow, the excessive pigmentation, and the prominence of recent degenerative lesions in the organs are much more like the changes of a primary hemolytic intoxication than of an aplastic anemia.

Gray Fox (Canis cinereo). ♂ Weight four pounds, adult, was in the exhibition two years, but in good condition until two weeks before death, when it stopped eating and rapidly fell away.

Diagnosis.—(Aplastic) Primary anemia. Zenker’s Hyaline of heart and skeletal muscles. Mucoid degeneration of bone marrow. Congestion of bone marrow. Atrophy of hemopoietic elements in bone marrow.

Hemosiderin pigmentation of liver. Atrophy of liver. Congestion of liver. Congestion and fatty infiltration of kidney. Patulous lumina in adrenal and absence of pars glomerulosa.

External appearance of coat good. Decomposition advanced in intestines. Skin and subcutaneous tissue faintly yellow. Poorly developed, dark muscles and fat. Respiratory tract normal throughout. Pericardium glistening, transparent, and pale, with no adhesions. Heart a little too pale, consistency slightly soft. Normal or slightly increased size of liver, with smooth surface and sharp edges, consistency friable, and of a brownish red with rusty coloring. Spleen normal. Kidney normal in size, shape, location, and consistency. Capsule strips easily, and of a faintly yellow, under general red, coloring. Adrenal normal. Mouth and teeth normal. Stomach, serosa and wall normal. Mucosa shiny, autolytic, muddy red. Ileum, agminated follicles swollen. Feces from colon examined microscopically. Pancreas normal. Bone marrow 103tibia and femur gelatinous and red, not slightest trace of yellow. Blood films from heart’s blood show poikilocytosis and anisocytosis; only one nucleated red.

Microscopic Notes.—Heart has torn but normal pericardium. No abnormalities of interstitial tissue or vessels. Fibres of normal width but show transverse markings irregularly since cytoplasm becomes hyaline and swollen in many places along its course. Nuclei prominent, slightly pyknotic. Zenker’s Hyaline.

Bone marrow consists of a matrix of granular or fibrillar mucoid tissue within the delicate reticulum of which highly developed capillaries are placed, together with stellate spindle and sealring cells. In a few places only are myelocytes recognizable and then in decreased numbers. Plasma cells sometimes found containing much blood pigment.

Liver.—Capsule normal; perilobular fibrous tissue only slightly overgrown, moderately infiltrated with lymphocytes and heavily with blood pigment. Arteries, ducts, veins, normal. Parenchymal cell a little smaller than normal with nuclei of normal type, and crowded with fine granules of blood pigment. Latter lie in usual pericanalicular position. Blood capillaries narrow, moderately congested and Kupffer’s cells also contain abundant pigment granules.

Thyroid.—Interstitial framework shows no fibrosis or cellular infiltrates. Blood vessels normal. Acini fairly uniform in size, none ever attaining large proportions, but some being distinctly below normal. They are uniformly filled with a very pale pink hyaline material which in some way gradually increases in color intensity toward one side, attaining in a few examples usual intensity of colloid. Lining epithelium is low cuboidal, shows no special hyperplastic features or atrophy.

Kidney.—Capsule normal. Interstitial tissue normal. Blood vessels slightly congested. Tubular epithelium granular, disintegrated and frequently contains numerous fat globules and obscured nuclei. Lumina of about normal size containing variable quantities of pink granular detritus. Glomerular tufts normal in size and appearance. Subcapsular space and Bowman’s capsule normal.

Adrenal.—Capsule and pericapsular tissue normal. Parenchymal cells throughout poor or practically free of vacuoles, such appearing in only limited portion of pars vesicularis. Interstitial framework and vessels normal. Structure of columns in pars vesicularis is peculiar in that they extend quite to capsule with no intervening pars glomerulosa, and again in that most peripheral parts are expanded at times showing a lumen, while deeper parts show broad cells extending fully across the column. Pars reticularis contains no pigment and medullary cells quite normal. Skeletal muscles show comparatively few fibres with transverse markings. Most are swollen, hyaline, lumpy, and have pyknotic nuclei. Interstitial parts show no inflammatory change.

Tissues treated by Prussian blue test for iron. Kidney, adrenal, heart found to contain none. Spleen, liver contain abundance. That in spleen responds to test showing that it is all iron containing. Two kinds of 104pigment found in liver. In periphery of lobule as much contains iron as that which does not, while in deeper parts iron predominates. Many times both kinds are recognized in one cell. On the whole it is the finest granules which contain more iron (are bluer) while iron free pigment occurs in bile canaliculæ. That in Kupffer’s cells stains strongly blue.

A review of these instances of grave anemia brings one to the conclusion that there is a strong similarity to the disease in man. Perhaps we have constructed a picture that is too narrow for the animal kingdom in general, but surely these few instances deserve to be distinguished from the secondary cases already presented if for no other reason than that no associated etiological condition was exposed. It was hoped in studying the anemias of lower animals, and this hope extends over all the subject of this book, to be able to throw some light upon causation. The thought of incorrect diet came at once, but we are confronted with the paucity of cases among our records. Moreover, secondary anemia from digestive and dietetic troubles is clear, but how we can use this argument for an essential change in hematopoiesis and natural hematolysis, is far from evident. It will be noticed that I have studiously avoided grouping any case with parasites among the primary cases, nor will there be found any evidence of generalized infectious disease. Most of the reported instances of pernicious anemia in the lower animals have been associated with one or other of these factors, although certain authors (Kitt, Hutyra and Marek) maintain that a causeless variety probably exists.

This condition is fairly well recognized by veterinarians as occurring among domesticated animals, but in the records of this Garden it has occurred rarely, indeed only once in a mammal and but five times in birds. It is interesting that, in the wealth of material at the disposal 105of Plimmer and his associates, only one case, a polecat with lymphatic leucemia, is noted, and but very few avian instances. Herewith is submitted the protocol of our single mammalian case; perhaps we have missed others of a mild grade dying during the early stages because their resistance to infection was reduced. Unfortunately, perhaps because of the postmortem changes, but more likely because it appeared at first as if we had to do with a case of generalized tuberculosis, the bone marrow in this case was not examined. Nevertheless the infiltrative character of the lesions, the absence of distinct tumors and the numerous mononuclears in the blood as seen in sections seem to justify a diagnosis of leucemia, in all probability of the lymphatic type. There follows this case one with similar gross and microscopic picture which has no visible increase of leucocytes, but a very distinct myeloid picture in many places.

Common Opossum (Didelphys virginianus). ♂ Adult. No evidence of illness. Found dead. Lymphatic leucemia (involving all viscera and lymph nodes). Diffuse nephritis. Both lungs have become entirely involved in a firm, gray-yellow mass not adherent to any serous surface. Practically no normal lung tissue is left. This seems like tuberculosis but no tubercle bacilli could be found in a good smear. Estimation of the normal cubic capacity of an opossum lung was made to be about five cubic inches. In this case not over one-half cubic inch remained respirable. Bronchial lymphatic glands were enlarged, firm, yellow gray, with no recognizable lymphatic tissue. Heart muscle was firm and flaccid, pale and striated. Liver very large, firm and tough, with smooth surface and sharp edges. Color pale brown. Section surface glistening, dry, smooth, opaque. Common bile duct patulous. Spleen, slightly increased, firm, tough consistency, capsule smooth. Section surface, smooth, firm, brown-red, pale pulp, prominent follicles, and trabeculæ faintly visible. Right kidney, slightly decreased, normal in shape. Capsule smooth, strips with difficulty, tears surface. Surface, granular, color brown, consistency firm. Thickness of cortex, narrow irregular, markings irregular and obscure. Small mass of fibrous material in cortex about 3 × 3 mm. like those in lungs. There are also numerous pale yellow gray areas in cortex and outer medulla, round and streaky, distorting the striated architecture. Right adrenal converted to a yellow gray mass like lungs. The mesenteric and retroperitoneal lymph nodes are firm, gray-yellow. This includes those under diaphragm and around cœliac axis.

106The histology of the organs may be described together. The infiltrate described is a densely packed mass of large cells with large, well staining nuclei and a very narrow rim of protoplasm. It is not limited by any definite wall or septa. It has no interstitial tissue. There is no blood supply in the densest masses but the walls of the blood vessels remain intact wherever the mass surrounds them. In the lungs it has involved all structures indiscriminately, and has destroyed practically all of the respiratory surface. It seems to follow by preference the peribronchial space. A few glands may be seen in the centre of this mass, but they are rapidly undergoing degeneration. In the liver the infiltrate is chiefly beneath the capsule extending inward but a very short distance. There are no large masses as in other organs but small infiltrates are seen at the portal areas. The spleen shows a diffuse excess of pulp cells and many of the cells above described, the difference being only in the size of the nucleus which is smaller in the pulp cells. There are very small round cells relatively. Follicles are absent, connective tissue not altered. Note states follicles prominent; this is due to nodal hyperplasia of the large mononuclears above described. The parenchyma in the kidney is anemic, the epithelium is slightly pigmented but this is probably not abnormal. Between the tubules especially of the outer layer of the medulla and medullary ray but also in the cortex and around the glomeruli are diffuse, irregular, infiltrating masses of the cells as described above. In some places in the kidney hyaline casts are being formed probably due to the degeneration of the epithelium by pressure. There are a few distentions of the tubules. The capsular space is free. In the neighborhood of the collections the capsules are a trifle thicker than normal. Lymph nodes, similar to spleen in that most of the bodies are thoroughly overrun with the large mononuclears. The sinuses, both marginal and internal, are practically obliterated by these cells. In the blood vessels of the lungs and liver there are many large mononuclears, perhaps not as large a number as might be seen in leucemia, but decidedly in excess of normal.

Common Marmoset (Callithrix jacchus). ♂ Adult. Had cage paralysis for two months before death and declined gradually from that time.

Diagnosis.—Bronchopneumonia. Myeloid hyperplasia of bone marrow. Myeloma in pancreas. Fatty degeneration of liver. Constipation. Nematodes in cecum. Animal is thin, skin bare in spots. Both lungs are pale pink with large areas of deep red consolidation. Heart is dilated, increased in size with firm, red-brown muscle. Liver is firm, red-brown, with smooth surface and sharp edges. Section surface is glistening, smooth and moist. Lobular outlines are clear by reason of pale lines. The gall-bladder is normal in size and contains fluid pale green bile; duct patulous. Spleen is normal in size, smooth capsule, soft, purple pulp, follicles small and faint, trabeculæ fairly prominent. Kidneys normal in size and shape. Capsule smooth. Section surface smooth and brown and firm. The glistening section surface has a narrow cortex, 107swells slightly, with prominent striæ. Intestines throughout are pale on serosa. Wall thin. Mucosa flat, pale pink. Contents creamy mucus in the upper intestine. Large intestine contains large masses of very firm feces. Cecum is distended with feces and a great quantity of nematode worms. They are not attached to mucosa nor does mucosa seem altered because of their presence. Skeleton and muscles.—Long bones of extremities break easily, but with snap. Skull can be dented with fingers. Bone marrow of femur bright red.

Microscopical Notes.—Liver shows moderate degree of fatty degeneration with capillary congestion. Kidneys negative. Some postmortem change in last two organs. Spleen, marked congestion. Hyperplasia of large lymph cell type, particularly in follicular centres. Blood destruction moderate. Bone marrow seen in condition of marked activity of myeloid type. Aside from enormous crowding of strands there does not seem to be any atypical cell. Intestines show practically no change. Same condition holds in pancreas. In several places in pancreatic ducts cross sections of nematodes may be found. In among lobules of pancreas is a well encapsulated cellular mass without particular architecture. It consists of cells of large lymphocyte or endothelioid series. There are numerous cells of size and staining characters of small lymphocytes. There are no megalocytes but there are some indistinguishable from myelocytes. This may be an intrapancreatic lymph node. One small lymph node found in section; it shows a picture quite like the marrow except for megalocytes. Blood vessels do not show an excess of leucocytes in free or coagulated blood.

Perhaps this latter case belongs to the aleucemic leucemias or pseudoleucemias. These two conditions are recognized by the difference in circulating leucocytes, a piece of information not at our disposal. The whole subject of hemato-lymphatic affection must remain unsettled in so far as a diagnostic name is concerned, for in very few cases has the blood of our animals at autopsy been in a state permitting reliable observations upon stained smears, because of coagulation, lysis or decomposition. After considering a few more of the diseases of the blood and marrow, the lymphatic apparatus will be considered. But there is a borderland to which a word might be devoted at this time, that group to which various names—Hodgkin’s disease, pseudoleucemia, general adenopathy, adenie, aleucemic leucemia—have been applied and which has been accepted as occurring in the domesticated animals. Since I have been occupied for several 108years in a study of this clinicopathological complex in the human being, such cases have been searched for most diligently, but without success. The New York Zoological Park records a case of Hodgkin’s disease, without specifications, in 1901, and at the London Garden a pseudoleucemia was found. The paucity of leucemia and of the aleucemic adenopathies in lower animals and their relative frequency in man excite speculation as to their interdependence; but more of this under the lymphatics.

The class Aves is rather better represented in the group of leucemias, but here the well known infectious disease may confuse the picture. The birds affected were Psittaci 3 (1 parrot, 1 parrakeet, and 1 amazon), Herodiones (stork) 1, and Galli (Gambel’s quail), 1. There was no close association of these cases either in time or housing. One of the parrots and the stork had a picture suggesting that given by Warthin for avian leucemia while the remainder presented greater evidence of a generalized infection, such as Moore described, associated with the finding of the B. sanguinarium; this organism was isolated once, but no secondary cases succeeded upon the death of this bird. It seems hardly profitable to quote protocols of this relatively unimportant condition, especially since it is fairly well known.

The separation of the two groups just specified might be discussed, however, for it is by no means certain that they are or are not different. When a pathological picture of leucemia gives a decided impression of an acute infection there are very prominent involvements of the viscera but no lymph nodal masses. On the other hand, in the cases with nodular masses corresponding to the scanty lymph tissue of birds, there is much less infiltrative involvement of viscera and less parenchymatous degeneration. This suggests that they are different 109processes, but an analogous contrast may be found in the pathologic anatomy of acute and chronic leucemia in man, and I am inclined to view them as stages of the same disease. In one of our infectious cases noted above the lesion was certainly myelogenic for the infiltrate in the organs and the cells in blood smears showed an enormous number of eosinophilic and basophilic polynuclears greatly in excess of normal. The study of two of our cases confirms the picture as given for lymphatic and myeloic leucosis by Ellermann^[18], but material corresponding to his lymphoidocytes or erythroleucotic group has not come to our attention. Cells with deeply staining basophilic protoplasm and a lymphoid nucleus are certainly to be found with reasonable ease in the avian marrow normally and, more than this, can be detected by careful search in nearly all cellular infiltrates of organs not leucemic in nature. Perhaps, as Ellermann states, they are collateral stages in normal erythrogenesis.

Since the foregoing conditions so vitally concern the bone marrow, it is but natural to give to this structure a separate consideration. From what is known of the origin, physiology, anatomy and regeneration of the marrow from the work of Ponfick, of Neusser, Bunting, Selling, Werigo and many others, it seems highly probable that the principal conclusions reached in the study of human medicine and experimental pathology, apply to the whole group of animals here under discussion. The peculiar arrangement already mentioned as encountered in the marrow of birds differs little if any from the erythropoietic centres seen in man after experimental anemia, although it may be somewhat more orderly. Myeloblasts or megakaryocytes are not numerously present in any order, but seem more prominent in the mammals than in birds. In so far as the mononuclear 110groups are concerned, one can state with reasonable certainty that they differ little throughout the animal kingdom. They occur in islands, strands, or infiltrate—like groups, are mixed granular and non-granular in character and, with exception of the frankly oxyphilic cells, are distinctly basic in tinctorial affinity. In a case probably myeloma, soon to be discussed, there is not a single acidophilic or multinucleated cell to be found in two sections. As might be expected from the greater eosinophilic content of the circulating blood in the Aves, greater numbers of such cells are to be found in the marrow and they are, understandingly enough, sometimes found in distinct nodes and groups containing mono- and polynuclear varieties. Concerning the platelets, no sufficient data are at our disposal to warrant a general statement. In the avian marrow they can be made out quite clearly, as in the blood, and have a greater diameter and a sharper, more chromatic nucleus than in the higher mammalian blood. Mast cells are quite common in lower mammals and birds, in whose blood they maintain an appreciable percentage, while in the marrow they stand out clearly. It is noteworthy, in the light of Graham’s statement that the hemic basophile is but a degeneration form of the eosinophile, that in the bird’s marrow, large mono- and polynuclear cells with both kinds of granules easily may be found by Romanowsky stain. An increase of eosinophiles, seen in avian as well as in human parasitism, is not necessarily accompanied by basophilia.

Hyperplasia and atrophy of marrow in the lower mammals follow much the same conditions as in higher groups. During acute general infections, as by the paracolon bacillus in carnivores, it is common to find a distinct increase in the mononuclear centres, while in suppurative lesions a polynucleosis results. The bird, however, responds less readily with leucocytes, judged by cross sections of blood vessels and the activity of the 111marrow. The latter may show a myeloid picture, but mononuclears without granules, with deeply staining nucleus and protoplasm, are usually more numerous; two cases recently studied, one of tuberculosis and one of pneumonia with general congestion, had similar bone marrow—pale homogeneous red with distinct mononucleosis, more outspoken, however, in the former case. Pigment is not common in the avian marrow.

The relation of the marrow to general conditions has been mentioned in the foregoing pages, but perhaps the following diagnoses will illustrate other connections seen among our records:

Bactrian Camel (Camelus bactrianus).—Hydatid disease of lung and liver. Hemorrhagic enteritis. Atrophic bone marrow. Calcified areas in thyroid.

American Gray Wolf (Canis mexicanus).—Cretinoid. Hemorrhagic external pachymeningitis with craniotabes. Secondary hyperplasia of thyroid with colloid. Chronic lymphatic hyperplasia. Chronic interstitial nephritis. Chronic enteritis. Osteogenesis imperfecta. Hemorrhagic bone marrow. Concentric hypertrophy and dilatation of heart.

Perhaps no pathological condition has given rise to more varied opinions than the tumor-like hyperplasias of the bone marrow, growths resembling bone sarcoma with and without giant cells—myeloma, chloroma, pseudoleucemia ossium and many others. In brief only two cases occur in our series which could be admitted to this category. There have been osteomata, but they were so clearly local tumors that they cannot be included in myeloid neoplasms that are assumed to be systemic in nature. Here is not the place to engage in a discussion of the correct classification and nomenclature since there are included only the aleucemic newgrowths usually assumed to originate from blood-making cells. The first 112case seems to be a myeloma because of the involvement of many bones and the infiltrates in the liver. Judging by the cross section of blood vessels there is no leucemia, but of course this is not final, although somewhat supported by the normal size of the spleen and lymph nodes; lymphatic structures need not be enlarged in myeloid leucemia although they usually are.

Beechy’s Gopher (Citellus grammurus beecheyi). Adult ♂ . Gradual loss of power in limbs beginning about two weeks ago. No other symptoms.

Diagnosis.—Multiple myeloma. Anemia. Acute parenchymatous nephritis. Chronic ulcerative gastritis.

External Appearance.—General condition fair, hair in good condition. Fully developed animal. Muscles contained no fat.

Respiratory Tract.—Thymus, large soft gray homogeneous. Both lungs are distended, pale, homogeneous, yellow pink, boggy, do not crepitate, but contain no edema. Lymph nodes, small soft anthracotic. Pericardium contained no fluid.

Abdomen.—No adhesions. Size of liver normal or slightly small, firm and pale brown-red. Architecture irregular showing areas of perfect homogeneity and others where lobules are clear outlined by paler interstices. Gall-bladder distended, contains brown fluid. Common bile duct, patulous. Spleen, normal or slightly small, consistency soft, capsule smooth, location normal; section surface, homogeneous pale pulp, faint trabeculæ. Kidney normal in size and shape, capsule smooth, strips easily, smooth brown surface; section surface glistening, opaque; consistency firm; thickness of cortex normal and of medulla normal; homogeneous cortex, glomeruli not visible.

Adrenal.—Narrow, brown, opaque cortex; pale brown, opaque medulla. Bladder, small quantity of cloudy urine showing albumin, bile and many granular casts, few hyaline casts. Teeth carious broken; mouth pale. Stomach distended; serosa and wall pale, contained gas; mucosa pale, flat, translucent except in pyloric segment where it is slightly thickened, irregular, opaque and there are several saucer shaped depressions covered with black, shiny material; these seem like sluggish ulcers. Intestinal tract throughout seems normal save for its pallor. Few natural fecal masses in lower gut.

Skeleton and Muscles.—All bones are irregular in thickness, very brittle and show in their length irregular swellings made up of periosteal growth and probably increase in marrow. The latter is pale yellow with punctate hemorrhages. Skeleton seems too soft to give support, but there is little deformity.

Microscopy.—Bone section shows a myelomatous growth of costal marrow, new myelocytes predominating. The cells are packed in disorderly fashion through the marrow. They are chiefly lightly granular 113but a few distinct promyelocytes are found. The hyperplasia is invading cartilaginous bone with absorption. In some places cartilage is of fetal type. Perichondrium is active but there is no round cell infiltration. Ossification is imperfect at costochondral junctions. Kidney shows granular and vacuolar degeneration of epithelium with flattening of tubular lining. Nuclei are for most part normal. Epithelium of tufts and Bowman’s capsule is likewise granular and vacuolated. Distal and discharging tubules seem to be most affected. No well defined casts are found.

Liver.—The fine markings mentioned in the notes correspond to areas of infiltration of large pale mononuclears without granules. There is no fibroblastic or polynuclear increase around them. Very small necroses seen in hepatic lobules. Very slight increase of connective tissue is noted.

This seems to be a tumor of true myelocytic origin; none of the cells was of the plasma type as usually depicted. The second case stands in the files as a myeloma, yet the full description and slides have been mislaid. It is cited briefly for record.

Samoli Ostrich (Struthio molybdophanes). Adult ♂ . Would not eat for three weeks.

Diagnosis.—Tuberculosis of lung, liver, spleen, kidney, mesenteric and cervical lymph glands. Myeloma of periosteum of pelvis.

Skeleton and Muscles.—Large tumor mass lying on inside of pelvis measuring about ten inches by twelve inches with a thickness of about four inches. It is sharply defined and separated from adjacent muscle by a capsule. Inner border is directly below the peritoneum, and outer border lies directly on bony pelvis. Traced to its origin it seems to come from pelvis yet tumor peels off bone easily, leaving a rough surface. The tumor is soft and succulent, of a red gray color and contains some fat and much irregularly placed masses of bony tissue.

SECTION V DISEASES OF THE LYMPHATIC TISSUES INCLUDING SPLEEN — Hyperplasia. — Lymphomatosis. — Local Hyperplasias. — Thymus. — Tuberculosis. — Tumors. — The Spleen. — Enlargements of Spleen. — Reason for Congestive Enlargements. — Inflammations. — Special Subjects—Amyloid. — Necroses. — Spleen in Anemia. — Spleen in Hepatic Fibroses. — Perisplenitis. — Tuberculosis.

Since we have followed diseases of the blood from the simple anemias to a place where mononucleosis in the circulatory system and in the fixed tissues is the prominent feature, another step reaches the area whence most of these cells emanate—the lymphatic system. The anatomical and physiological position of the lymphatic circulatory apparatus is closely analogous in the classes under discussion, and it stands in an anatomico-clinical sense, closer to the hematopoietic system than to any other structures, throughout the whole animal creation. This anatomical division of the circulation is closely comparable, for pathological purposes, in the mammals whereas in the birds one finds noteworthy variations. In the class Aves lymphatic radicals are extremely numerous, the plexuses in the extremities and thorax perhaps being complemental for the rather scantily supplied blood vessels. About the fibulo-tibial and femoral muscles the tiny lymph vessels form an extraordinarily dense and intricate lacework, a replica of which may be found in muscles of the upper limb, while in the pelvis and thorax a rich plexus is distributed around both kinds of blood vessels and also lies within the walls of air sacs. The air sac walls in the chest display lymphatic lines very well in birds that have been for many years exposed to railway dust, the natural pearl gray glistening membrane looking as if black pepper had been evenly dusted over it. The lymph glands or compound nodes so easily discovered in mammals are practically absent in birds. Along the large thoracic vessels and in the pelvis of some anserine and struthious varieties, small illy defined masses of lymphatic tissue may be discovered by careful 115search but they do not possess nodal arrangement and capsule. Lymph follicles on the other hand, are quite numerous in the respiratory, and especially, the intestinal tract. Groups of follicles may also be found in the lining of the upper ends of these tracts in such situations that the names faucial, pharyngeal, or even tubal tonsils are justly applied. I do not find any reference to a lingual tonsil in birds, but this structure is found, with of course many modifications, down as far as the monotremes. The lymphoid tissue of the nasopharyngeal region is so placed in animals as to be exposed to aerial and food infections, just as it is in man. It is, however, noteworthy that chronic inflammations leading to hypertrophy or to obstruction have not come to our attention. There is only one diagnosis of chronic tonsilitis in our records, a determination based upon the nodular red-brown prominence of the tonsillar region, but there were no true hypertrophy and areas of fibrosis combined with necroses as seen in human medicine; this case concerned a Chacma baboon.

In so far as the reaction to infectious or toxic agents is concerned there seems to be a fairly uniform character through the mammalian groups, but in the Aves there are a few differences worthy of mention. It is at once admitted that these observations upon birds are based upon a very few sections of isolated lymphatic tissue, but they are supported by records of the changes in nodes in mucous membranes and viscera, and by those in the spleen. The first and perhaps most noteworthy difference is in the paucity in birds of large mononuclears of the endothelial type. Their position in chords, sinuses and germinal centres is taken by deeply staining mononuclears, of the size and general character of large lymphocytes as seen in the blood. The hyperplasia in the follicles is much more dense but it is outdone by that in 116the chords. Since the nodal tissue of birds is not so sharply delimited by some sort of capsule, it is but natural that the hyperplasia should be diffuse; in the intestinal wall it may extend laterally twice or thrice the width of the normal follicle. Necrosis, unless the disease be mycotic, tuberculous or parasitic, is uncommon.

It may be well to discuss for a space the reaction to infection of the thoracic and intestinal lymphatics in mammals. The amount of lymphadenoid tissue in the mediastinum is very great in some mammals, notably the Ungulates, while in others, the Rodents and Primates, for example, it is not so plentiful. Nevertheless the gross and minute changes are usually of the edemato-exudative type—large, pink, soft, moist glands. In the abdomen, on the other hand, one usually finds well outlined, firm, yellow nodes in the mesentery and behind the peritoneum. This is not only to be discovered in various chronic diseases of the intestine but even in acute, so-called toxic enteritis seen in carnivores from food poisonings. One must therefore ask if the local nodes abundant in the intestinal mucosa do not take up the poisons which cause the acute hyperplasia and are in turn backed up by the stalk glands. Even in so acute and overwhelming a disease of the intestine as hog cholera (which we have not had here) the glands retain their general structure, although hemorrhagic, while in late stages they become firm, sharply outlined and pigmented. In birds there may be swelling of the omental bursæ, but as there are no lymph glands no masses are found.

The response on the part of the lymphatic tissues as a system, or some large section of this system, is shown in the following figures. It is our practice to include in the diagnosis general acute or chronic lymphadenitis or inflammation of a large drainage area. Acute changes have been mentioned 103 times, in which the important orders are represented as follows: Primates 21, Carnivora 46, Ungulata 15, Rodentia 3, Marsupialia 13, 117Pinnepedia 4. Chronic changes are mentioned 43 times as follows: Primates 7, Carnivora 19, Ungulata 14, Marsupialia 1, and Pinnepedia 2. This great proportion among the Carnivora does not indicate that they have more lymphatic structures for such an advantage is probably possessed by the Ungulata, but perhaps should be interpreted as an evidence for this order of the ready response to irritation on the part of the tissues in question. They probably suffer more, as we shall see later, with inflammation affecting drainage tracts. The hyperplasias or inflammations included in the figures above most often accompany gastroenteritis, pulmonary diseases or long standing infectious processes such as arthritis, while there are also lymphatic enlargements both local and general, associated with skeletal degenerations (rachitis-osteomalacia) and with thyroid disease. The former may be described as lymphadenitis, the latter as lymphatic hyperplasia.

Unlike lymphadenitis, a condition associated with some definite infectious or toxic cause, systemic hyperplasia of the lymphatic tissue may be apparently primary and causeless. In a pathological and clinical sense alike these hyperplasias are protean in their manifestation, making a satisfactory classification extremely difficult. For our purposes they are divisible into acute and chronic, associated with an increased number of circulating lymphocytes and without such a lymphocytosis.

The first, acute systemic lymphatic hyperplasia, is known in man as status thymicolymphaticus, a well recognized condition chiefly encountered in youthful males having some of the stigmata of the opposite sex. There is no record, nor have I any recollection of a pathological state in a wild animal comparable to this condition.

If acute generalized lymph node increase be associated with lymphocytosis, acute lymphatic leucemia exists; there is no case in our records. Chronic enlargement of lymph nodes with increase of circulating mononuclears is 118chronic lymphatic leucemia; a case of this has been cited under leucemia.

Chronic enlargements of the lymphatic tissues without leucemic blood present a bewildering number of varieties, the best known names of which are Hodgkin’s disease, aleucemic leucemia, pseudoleucemia and lymphomatosis. On occasion they are at first localized tumors, being generalized only late in the course; under these circumstances they are usually classed with neoplasms in the form of leucosarcoma and lymphosarcoma. Examples of lymphatic disease answering the above description are limited to two, but even these must be explained in certain particulars. There has already been quoted under leucemia a case of a common Marmoset (Callithrix jacchus) which was probably aleucemic leucemia of the myeloid variety; the enlargement of lymphatic nodes was trifling. The case to be cited answers in most respects to the descriptions of systemic lymphomatosis, but there were found two conditions, enteritis and parasitism, which might be responsible for sufficient general toxemia to stimulate lymph nodes and follicles to a state of active growth. Even accepting these two cases as examples of this group, it is very plain that chronic systemic primary lymphatic hyperplasia is an exceedingly rare entity in wild animals. There has been no case resembling Hodgkin’s disease of man.

California Hair Seal (Zalophus californianus). Young ♂ four months old. Appeared to be in good health, no loss of flesh or activity.

Diagnosis.—Lymphomatosis. Fatty degeneration of kidneys. Emphysema. Chronic follicular and catarrhal enteritis. Nematodes in intestines.

External appearance good. Both lungs distended and are tense; it seems almost like a spastic dilatation—a simple emphysema—beneath pleural surface are many minute petechiæ. Lung mottled red and gray. This color is present on section. Lobules clearly outlined and separable with fingers. Bronchi and vessels widely open, the latter containing small amount of fluid blood. Lymph nodes—Mediastinal, tracheal and those visible in neck are variously but definitely enlarged, firm, irregular 119and roughly nodular, both in appearance and to touch. On section they are red and gray, follicular border not preserved and merging with medulla; connective tissue visible; gray juice expressed. Pericardium normal. Epicardium, glistening, transparent and pale. Heart position, size and interior normal. Abdomen contained no adhesions or fluid. Pale brown-red, firm liver with smooth surface and sharp edges; markings not clear; section surface smooth; watery blood expressed from section. Gall-bladder normal, contents limpid, brown. Common bile duct patulous. Somewhat enlarged spleen, soft, yet resilient; capsule smooth; section surface pulp homogeneous brown-purple; follicles gray, slightly enlarged, clear, sharply outlined; trabeculæ faintly visible, more prominent where they are near follicles. Kidney normal in size, shape and location, with smooth, pale brown surface; capsule smooth, strips easily, section surface glistening, consistency soft yet resilient; thickness of cortex slightly wide, of medulla normal; individual lobules clear yet no increase of connective tissue between; pyramids quite pale; top of medulla a little darker; cortices, pale, striæ quite faint and seem irregular; glomeruli not visible. R. Adrenal—In upper pole are two cysts about 1.5 and .8 cm. across; no scar at this point. L. Adrenal—Wide pale purple, regular homogeneous cortex under very dense capsule; medulla reddish brown, homogeneous, quite bloody. In left adrenal is a pale gray, fairly well outlined area between medulla and cortex at upper pole about 3 mm. across.

Stomach.—Contains glass and stones; mucosa, soft, smooth, flat, yellow and pink, translucent rugæ; cardia about normal; pylorus, valve prominent but probably not hypertrophied. Duodenum—Beginning at pylorus and extending through to ileum where follicles commence, intestine contains small amount white, creamy material, serosa negative, mucosa smooth flat, pale pink, translucent. There are small nematodes, probably uncinaria, some of which are attached quite firmly. Here and there throughout the gut are bits of thickened mucosa or submucosa, 2–5 mm. across. Some of these have a tiny opening from which clear fluid can be expressed. Ileum shows smooth flat translucent mucous membrane; empty; individual follicles faint but discernible. Colon reddened mucous membrane, nematodes and little mucus. Pancreas, soft, normal in size and position, color pink gray. The lymphatics of peritoneal cavity are all enlarged; most of retroperitoneal are also. Regional lymph glands are also enlarged. The description given for mediastinal answers here. The glands of mesenteric stalk present chain of sausage-like masses. Glands in mesentery are but slightly affected. Glands within and without peritoneum at kidney are especially enlarged. Large gland behind stomach and pancreas and in front of upper end of spleen is much enlarged, thick and roughly circular; it shows much fibrosis. The regional glands are distinctly enlarged but proportionately not so much as the internal ones. Smear of juice expressed from peritoneal glands shows large and small lymph cells in about proper proportions. There are a few plasma cells. No granular cells.

120Smear from bone marrow shows enormous number of premyelocytes and mast cells. Polynuclears in their early stages are not numerous. Small groups of lymphocytes, lightly packed together, noted here and there. Blood smears unsatisfactory.

Microscopical.—Lung shows distended vesicles with considerable congestion of septa and in some places red blood cells in alveoli.

Kidney.—Glomeruli contracted, relatively anemic; capsule negative; epithelium throughout in state of granular degeneration probably fatty; connective tissue not increased.

Intestines.—Show slight hyaline change in muscle fibres and nodular degeneration and disappearance of protoplasm, leaving bare nuclei and outline of the cells; submucosa loose; mucosa shows infiltration of round and plasma cells, diapedesis, degeneration and desquamation of epithelium. Section of ileum shows a hyperplasia of lymph follicles with active centre in which large endothelial cells predominate. Small swellings in submucosa consist of chronic granulation tissue, but there is no foreign body and no evidence of preëxistence of a lymph follicle.

Lymph nodes loosely arranged but in places solidly small lymphoid; chords and sinuses contain chiefly small lymph cells in which are some mast and plasma cells; follicles small and loose, and centres contain chiefly large lymph and plasma cells; connective tissue not increased yet there are some fibroblasts in follicles.

Spleen.—Shows almost entirely hemorrhagic pulp; blood destruction not active; follicles large and made up of about equal mixture of small lymph, plasma and large lymph cells; connective tissue prominent probably because of excess of blood around it.

In this group and touching the purely hyperplastic, come the hypertrophies of the lymphadenoid tissue of the nasopharynx; this can be disposed of by stating that no true chronic hypertrophies have been seen. With most cases of gastroenteritis in ungulates, and many in carnivores, there is a swelling and redness of the tonsillar region but an exudative or necrotizing process does not occur.

The thymus is rarely visible in our specimens but when found has usually been normal. An increase in size and a decrease of consistency of this organ is noted in marasmus (inanition) from failure of care of the young 121by the parent, but so far as can be determined this has not been adequate to cause tracheal compression. In a few cases of rachitis in the canines, the organ is large and pale along with the rest of the lymphatic system. In one of the tumors of the mediastinum to be discussed, the suspicion arose that the growth originated in the thymus; adenomata and sarcomata have been described in the lower animals.

Tuberculosis of the superficial lymph glands is rare as an independent lesion in the lower animals. Dr. C. Y. White was fortunate in seeing a monkey with a chain of fibrocaseous nodes in the cervical region, upon which before death he offered the suggestion that it was of tuberculous nature. In Primates almost all drainage glands exhibit some miliary or caseous process. One monkey rejected upon the tuberculin test had what was apparently a primary lesion in the glands at the tracheal bifurcation. In the Ungulata, lymphatic tuberculosis assumes two forms, the caseous and the cellular. The former is generally understood while the latter is more uncommon. It is occasionally seen in the “fungous tubercle” of cows, but we have seen it in deer and in another order, Carnivora. In the latter, tuberculosis being uncommon, examples in the lymph nodes were noted but twice, once caseous and once solid; this latter was made up of firm, homogeneous yellow pink masses of glands in the mediastinum, showing under the microscope solidly packed epithelioid and giant cells.

Lymphatic tuberculosis in the birds is rare; only one case is recalled (unfortunately record cannot be found) as small yellow, discrete firm nodules in the mediastinum and neck. The minute picture was of a solid arrangement of large vacuolated mono- and polynucleated cells which were so packed with bacilli that the preparation could not be decolorized.

The neoplastic enlargements are represented by a lymphosarcoma of the mediastinum in a Dorcas Goat; there were secondary growths in the liver, the kidney and several isolated lymph glands. Secondary growths from original tumors not in the lymphatic system are curiously rare, certainly much less frequent than is found in the human being. In ninety-two tumors which are known to give metastases, only three involved the lymphatic glands and only one of these could be considered as involving nodes not in the ordinary drainage pathway.

The spleen is an organ whose exact position in the scheme of things remains mystifying through the whole series of animals. Its functions have been arrived at largely by exclusion, somewhat by conjecture and speculation, while the acceptably proven duties are indeed few. Although this is not the place to enter into a discussion of all the points at issue concerning the anatomy and function of the organ, a few facts might be mentioned of comparative and perhaps pathological value. While the spleen has been looked upon always as the origin of blood cells in the embryo, cases in man are on record where no spleen was discovered, a condition suggesting that its absence is not incompatible with life; that such is the case is obvious for experimental or therapeutic removal of the organ is well known.

It was suggested by Virchow that at times the spleen assumes the duty of the bone marrow and the swelling of the viscus in certain anemias seems to support this statement. However, there is no physical relationship between the size of the animal and that of the spleen, nor between the available quantity of bone marrow, the obvious richness of circulating blood and amount of lymphatic tissue. This is well shown in the water mammals which have a great deal of blood in vessels and viscera yet their spleen 123is relatively smaller than birds of somewhat comparable size (the ostrich, for example). The Carnivora and Rodentia among the mammals, have quite large spleens proportionately, while comparable birds, Accipitres and Striges, have relatively small ones, and an absolutely small amount of marrow.

Another anomalous example of the function of this tissue is found in the hematopoiesis of birds. While there seems to be some evidence that in the spleen and liver red blood cells may be formed, there is perhaps at most times sufficient bone marrow to keep the blood cells at a proper number. There is no inverse relation between the amount of bone marrow and that of splenic bulk; that is in diving birds with their hollow bones the latter is no greater than in gallinaceous birds which have abundant marrow in all the skeleton.

It has been suggested that the spleen supplies an activator for pancreatic ferments. This receives a sort of support from the greater size of the organ in carnivores and smaller relative size in ungulates, since in the former concentrations of digestive enzymes are more often needed. Because of the greater excretion of iron in splenectomized animals or those being starved, Fischer has thought that the spleen has some power to metabolize this element; this receives some support from the statements concerning the size of this organ in the carnivorous orders. From experimental studies it appears that some relation exists between the lymphocytes and resistance to implanted tumors. If one apply this idea to the amount of lymphatic tissue and the incidence of spontaneous new growths, it is found that no definite relationship is discoverable either in terms of size of spleen or richness in lymphatic nodes. Carnivores, rodents and marsupials show a high tumor incidence and have a good lymphatic supply. Aves, on the other hand, with a poor nodal apparatus and a variable splenic bulk, show many fewer 124tumors than do the mammals. The mononuclears of avian blood rise normally as high as 60 per cent., of which 40–45 per cent. are of the small size.

The size of the spleen is subject to great variation not only within orders but actually within genera; it even seems that one sometimes sees two or three members of a species kept in the same enclosure, maybe with the same disease, maybe without any obvious disease, yet with definite variation in the size of the organ. This irregularity is recognized by veterinarians (Hutyra and Marek) who ascribe it to some unknown disease, past or present, and to normal variation. The lack of uniformity is seen more clearly in birds than mammals. In the former it might be due at times to low grade or inactive parasitism or, conjecturally, to toxins from incorrect diet; we shall see later that infection and intoxication seem to have a different effect. Some writers have mentioned the possibility of an idiopathic splenomegaly (?), a condition associated in youthful human beings, with anemia and lymphadenopathy, and occasionally going over into a sort of leucemia. The existence of such a condition is difficult to admit or deny; we have met nothing which could not be aligned in some fairly well defined group. Birds have a relatively larger spleen than mammals and in addition the organ seems to respond more actively in infections or intoxications, since it may reach, under active stimulation, a size ten times that of the normal organ.

Acute enlargements of the spleen, be they of congestive or “inflammatory” nature are quite common among the lower animals, a fact that is recognized in veterinary medicine. Congestions of the spleen are most often seen during acute infections and diseases of the heart and liver. The diagnosis has been made among 125mammals proportionately more than in birds, 27 or 1.5 per cent. to 35 to 1 per cent.

Perhaps this is partly due to the circulatory anatomy since in the former the arterial and venous supply is usually by one large vessel of each kind, whereas in birds the splenic branch of the cœliac axis breaks up into several small arteries and the venous return is accomplished by numerous venules some of which reënter the posterior cava almost directly, others joining with the mesenteric to form the portal; by this arrangement a more elastic system is assured. The same condition is found when analyzing the records of chronic passive congestion; in eighteen recorded cases, fourteen were mammals and four birds. In these cases the principal associated pathological lesions were pleural and pulmonary in seven, cardiac in three, renal in three and hepatic in four. While the anatomy of the splenic blood supply may help to explain the small number of congestions in Aves, it will not answer for the inflammations which occur in large numbers in this class; this will be discussed in the following pages.

Hemorrhage and infarction of the spleen are not very common, there being eleven of the former and ten of the latter and all occurring with the same indication or history of infectious disease; in one case, an opossum (Didelphys virginiana) an injury probably caused a massive hemorrhage shaped like an infarct. It is, however, curious that of the twenty-one cases only five occurred in birds, of which only one hemorrhage was in the shape to which the term infarction is best applied. There have been, as one might expect, a few cases of infected infarction, with abscess. It is perhaps worth noting that no case of hemorrhagic cyst or inspissated coagulum has been seen. Only one case of rupture is recorded secondary to acute splenitis during an acute septicemia.

It has been the practice at this laboratory to classify splenitis in three ways, (1) acute diffuse splenitis—general congestion with perhaps small hemorrhages, swelling but retention of general architecture and with no undue prominence of the follicles; (2) follicular hyperplasia—where this is the prominent gross and minute finding, the pulp being less pronouncedly involved; (3) acute splenic tumor—where the organ is greatly enlarged but with loss of the usual markings. Perhaps this separation is not warranted upon a strict etiological basis, and yet as we shall see it holds true fairly well in the toxic and infectious lesions. Moreover, from the following list it is evident how the various orders call upon the splenic tissue in disease.

The points to draw from this chart are first the greater variety of lesions seen in the birds, which apparently 127make greater use of the organ in defence, and the preponderance of acute diffuse hyperplasias in mammals. It is noteworthy that the Primates and Marsupialia show more of the acute hypertrophy of the spleen going under the name of tumor. It would be interesting and valuable to be able to discover exactly what determines and constitutes the conditions usually termed hyperplasia and inflammation of the spleen and an attempt was made in this direction by tabulating the data from Table 7 in terms of each diagnosis, classifying these latter also as infectious and toxic. The results of this effort are not conclusive, and while they permit of some discussion of the lesions, do not allow finished conclusions. The figures obtained by study are not illuminating. One can state, however, that in infections, either specific or not specific, more elements of the spleen were engaged in the process than when the condition did not resemble a communicable disease, but might be called toxic. Under the former condition the diagnosis of splenitis or acute tumor predominated, while under the latter follicular hyperplasia is more often recorded. Anatomical alterations in these two groups are described in the definition given in a previous paragraph and deserve no special discussion except in so far as they concern the changes in the avian splenic tumor when under magnification.

Microscopically there is a total loss of the relations in the acute splenic tumor of birds, the chords and follicles being replaced by a rather regularly arranged mass of small and large mononuclears, granular cells of the circulating types and red blood cells; pigment always seems increased. Endothelial cells do not take part in the general mass of the organ but along lymph and blood vessels their bulk and number are increased so that if the packing be not too dense one may find double lines of these cells passing through the hyperplastic tissue. There is, however, a group of seven cases (six birds) to which the term endothelial hyperplasia in the spleen has been 128applied. All of them show an unusual prominence of the vascular linings and of the follicular centres and perivascular areas; besides this there is a moderate general hyperplasia. An examination of the history and autopsy results in the birds indicated that they had all suffered with some rather protracted intoxication and showed a moderate anemia (four of the spleens were well pigmented).

The more chronic changes of this organ, be they moderate or of a grade to which one must apply the term fibrosis, are rather uncommon when one considers the number of animals with prolonged infection, anemia, skeletal diseases and hepatic cirrhoses; these are the conditions that take a prominent place in the associated pathology and history. There is no essential difference in the organ throughout the animal kingdom, and one may find as far down as the struthious birds analogies to the processes of domestic and human animals.

Amyloid changes in the spleen have occurred in the following orders: Primates, Carnivora, Rodentia, Marsupialia, Passeres, Galli, Gaviæ, and Anseres, fourteen cases in all. This infiltration is usually ascribed to long continued suppuration or chronic infection, every one admitting, however, that once in a great while a case is seen wherein no cause can be discovered. In this laboratory we have a high percentage of cases without adequate accompanying pathology so that we have called six of the above cases primary or idiopathic. The gross appearance of the spleen is in all these cases that of an enlarged, firm, homogeneous body without the sago spots usually described for this change. Microscopically the infiltration occurs first in the vessel walls, thence spreading to the sinus walls and reticulum. Joest in discussing this 129infiltration^[19], states that it is comparatively rare among the domestic animals, where it may appear under the usual conditions or as a primary affection; it seems at times to follow unsuitable feeding. According to this author, the “sago” type is more common than the “bacony;” this has not been our experience. The most conspicuous example is given here.

European Badger (Meles meles) Adult ♀ . Gradual failure for two weeks.

Diagnosis.—Amyloidosis. Chronic parenchymatous nephritis. Emphysema of lungs.

Muscles atrophic; fat scanty. Heart is dilated and muscle is red-brown. Aorta is jaundiced and there is a small patch of atheroma near the anterior leaflet of aortic valve and about 5 mm. above it. Abdomen contains a slight amount of clear fluid, no adhesions. Liver is normal in size, smooth surface, sharp edges, firm consistency, yellow color. The section surface is glistening, smooth and moist. The spleen is very hard, greatly enlarged (25 × 6 × 2 cm.) and lies across the abdomen over the intestines. It is pale red and very bacony. In iodin the tissue stains a mahogany brown. The kidney is normal in size. (5½ x 3 cm.). The capsule is smooth and strips easily leaving a smooth, yellow surface. Organ is firm. The section surface is glistening, has a relatively narrowed cortex and relatively wide medulla. The glomeruli are barely visible but stain a mahogany brown in iodin. The adrenals are 12 × 10 × 4 mm. The cortex is wide, dull yellow and regular. The zone beneath fades into the cortex although rather abruptly. The centre of both glands is occupied by an irregular pale yellow, sharply outlined nodule suggestive of solid medulla, tubercle or tumor. The zone between cortex and this is gray, irregular and firm. This is practically a normal figuration. The stomach is empty, mucosa apparently normal. Intestines were not opened but serosa seems normal; when opened after Kaiserling fixation they seem normal. The pancreas is normal in size, firm and pale. Lymphatics of the mesentery are slightly enlarged, soft, homogeneous pale yellow.

Histological Notes.—Lung seems somewhat atrophic and there are some vesicular ruptures. One small patch of amyloid found in blood vessel wall. Liver shows slight capillary congestion and granularity of parenchyma. There is a marked blood vessel amyloid deposit not only in interlobular spaces but in intralobular capillaries. Spleen, no trace of splenic tissue recognizable in section. It is composed of more or less eosin-staining material surrounding single, or small collections of round or plasma cells. Kidney shows marked amyloidosis of glomeruli and slight deposit in blood vessel walls and in the increased connective tissue. There is a general moderate fibrosis; irregular tubules; low 130epithelium and hyaline casts. Heart muscle fibres are small and stain deeply. No amyloid in section. No pigmentation although section is suggestive of brown atrophy. Adrenal is practically negative. There seems to be slightly more connective tissue than normal but parenchyma may be considered normal. At one place in the cortex there are some structures of deep layer included in vesicular layer. This seems like a structural malformation.

Focal necroses of the spleen affecting chiefly follicular centres but also chords, are not at all uncommon in avian spleens, especially where parasitism occurs, not only with hemic protozoa and embryos, but also with intestinal or visceral nematodes and trematodes.

The spleen in the anemias shows much less definite change than one would expect. In the secondary form of anemia among mammals one finds a slight excess of pigmentation and an occasional fibrosis but often the size of the organ is recorded as normal. When the impoverished blood seems secondary to skeletal degenerations there is a diffuse or follicular enlargement. In the birds, on the other hand, there is nearly always some grade of enlargement which is due in the well studied examples to a richness of blood cells. There may be a slight increase in follicles, but these bodies are usually small and solid. In two instances a prominence of large endothelial cells was discovered. Pigment is seldom increased, but it may be very excessive.

In the primary anemias little more than the above is to be found. Fibrosis is more evident and perhaps pigmentation less so, but the variations are more of degree than kind. The spleen in leucemia can only be discussed upon the case already reported (q. v.).

Fig. 7.—EUROPEAN BADGER (MELES MELES). PRIMARY AMYLOIDOSIS. THE ENORMOUSLY ENLARGED SPLEEN IS SEEN LYING ACROSS THE STOMACH BELOW THE LIVER, WHICH ORGAN IS EXCEEDED IN SIZE BY IT.

The fibroses of the liver are not infrequently associated with some enlargement of the organ under discussion. At this laboratory hepatic cirrhoses are divided into Portal, Biliary, Fatty, Perilobular and Vascular. By a study of the spleens in these cases a few facts have been obtained. In mammalian portal cirrhoses there is usually a very moderate but definite increase in the size of the spleen due to connective tissue increase in the trabeculæ and reticulum, with very small compact follicles. Among the birds the organ seldom shows more that a moderate congestion and diffuse hyperplasia. In the mammalian biliary cirrhoses there is almost without exception a definite enlargement due to fibrosis and follicular hyperplasia. Among the birds the process is very far from uniform, there being just as often no change, as a congestion and hyperplasia, or as a mild fibrosis; it is notable, however, that pigmentation is commonly met in this class. No noteworthy change is met with in the spleen of fatty hepatic cirrhoses. We have no record of cyanotic induration of the spleen accompanying a similar condition in the liver. When the condition of perilobular hepatic fibrosis has been met a distinct increase of the splenic pigment is usually found. In reviewing the facts in this paragraph one is forced to the conclusion that, with the exception of the frank infective cases, there is no definite relation of the splenic changes to those in hepatic cirrhosis, a fact made perhaps the more significant in view of the idea held in some quarters that the primary change in this pathological process occurs in the spleen.

Perisplenitis of an acute or fibrosing variety as a part of peritonitis or as the result of an injury to the splenic region, has been encountered on numerous occasions and offers nothing worthy of comment, but the so-called “sugar-icing” spleen, associated with perihepatitis and general peritoneal thickening, and with an obscure relation to tuberculosis has not been seen. As we shall learn later peritoneal or massive intestinal tuberculosis is not 132common in the lower animals. A diffuse fibrous thickening of a pearl gray glistening appearance, has occurred in five monkeys harboring the Filaria gracilis in the peritoneum.

In tuberculosis of this organ the capsule is almost invariably thickened over the nodules, but not over the whole organ and rarely in the diffuse variety. There is almost always, however, in this prolonged infectious disease some reaction on the part of the spleen, particularly when several other viscera are involved. In such cases a low grade of general hyperplasia and fibrous tissue increase is found. This is especially true in the Primates and Carnivora in long continued pulmonary tuberculosis, and it is in this form that one does not often see tuberculous lesions proper in the spleen itself. Tuberculosis of the spleen is not very common in adult human beings and domesticated animals, while in the young it is seen in a fairly high percentage of cases. In the wild animals this organ seems much more susceptible to the settling of tubercle bacilli as will be attested by the facts to be cited, and yet there are some conspicuous exceptions to this statement. Just why certain groups, or orders should show splenic tuberculosis very frequently while others fail to do so is far from clear.

The appearance of the lesion is fairly comparable throughout the animal kingdom, variations among the Aves being chiefly in the more frequent occurrence of the diffuse tuberculous splenitis. Miliary, caseous and conglomerate masses occur separately or together and without very distinct relation to other pathological involvements.

The relative incidence of tuberculosis in the spleen is set forth in the section devoted to this infection, but may be mentioned here in a general way. The organ is about equally susceptible to the disease in mammals and birds 133according to the figures, but the high percentage for the former is due to the frequency with which tuberculosis is met in the Primates. With this order deducted there is no doubt that the avian spleen has a greater vulnerability for the tubercle bacillus than has the mammalian organ. Rodentia as a mammalian order stand next to the Primates, whereas the Carnivora and Ungulata relatively seldom show splenic tuberculosis. Among the Aves one finds that Columbæ, Galli and Accipitres have the highest splenic susceptibility, but beyond this one hardly dare venture because of the irregularity in the number of specimens seen at autopsy. Suffice it to say that a greater number of cases of tuberculosis are seen in the spleen of the class for which the intestinal origin of tuberculosis appears most important.

In the cases of actinomycosis and its congeners, such as the Kangaroo maxillary mycosis, which we have seen at the Garden, no specific changes have been seen in the spleen, unless a single or double nodule of the same variety as the original focus may be considered specific. Such was found in two cases, one a tapir with low grade inactive actinomycosis, the other a kangaroo with maxillary streptothricosis. Two deer came to autopsy with a gross picture suggestive of anthrax; no bacilli could be found in the semifluid spleen, but a member of the hemorrhagic septicemia group was found. The latter group of infections has been fairly well represented, although not in epizoötic form, and the almost invariable splenic change has been that already discussed as diffuse splenitis. Three secondary tumors are recorded, two cancers and one renal adenoma.

SECTION VI THE RESPIRATORY SYSTEM AND ITS RELATED STRUCTURES — Rhinitis, Sinusitis. — Mycosis. — Larynx. — Laryngitis. — The Bronchi. — Bronchitis. — Bronchiectasis. — The Lungs. — Congestion of Lungs. — Pneumonia. — Production of Insular Pneumonia in Birds. — Abscess and Gangrene of Lung. — Pneumonokoniosis. — Infarction of Lung. — Emphysema. — Tumors. — The Pleura.

It is customary to divide the descriptions of normal and diseased conditions of the upper entrance to the body into respiratory and alimentary parts, the nose, nasopharynx and larynx belonging to the former, the mouth, buccal cavity and pharynx to the latter. As a matter of fact they can for most purposes be considered as the structures contained in the anterior head and furthermore their pathological states are more often followed by extensions into or implications of the respiratory organs proper than of the alimentary tract. From a comparative standpoint the incidence of specific infectious diseases and of the involvement of accessory nasal sinuses present the most interesting subjects. There are several infections, believed to be specific, observed among domestic mammals and birds but their actual individuality has hardly been unexceptionally proved. This refers to the communicable rhinitis of cows, pigs, rabbits, and birds, especially parrots, the follicular catarrh of horses, and croupous nasopharyngitis, all of which have been ascribed to a particular virus, without finished evidence in many instances. Some of these diagnoses doubtless cover or are confused with the early symptoms and signs of the disease of protean manifestations, distemper, and indeed the Bact. septicus and relatives of the bird cholera organisms are reported as being responsible for them. No intention of excluding well recognized entities like bird diphtheria, foot-and-mouth disease or influenza, exists. I shall refer below to small groups of epizoötics which do not conform strictly with word pictures drawn by Hutyra and Marek, Moore, or Ward and Gallagher.

The nature of inflammations of the nasopharynx suggests at once that there may be some anatomical reason for their distribution and character. A general review of the anatomy of the mammalian and avian nasopharynx reveals the relatively greater space in the former, especially in the passage from the nose to the pharynx, and emphasizes the exposure of the opening of the upper larynx in the bird, lying as it does in the posterior part of the tongue and surrounded by the constrictores glottidis. A dissection of the accessory nasal sinuses exposes the relatively large size of these spaces in the lower mammals, and the capacious openings into the nasal cavities.^[20] In the Primates and Lemures the anatomy more closely resembles that of man, the sinuses being relatively smaller and the communicating passages narrower. In the bird on the other hand, while the sinuses may be extensive in some they are usually small, yet in all the communication with the turbinate area is by a narrower slit or tortuous canal, frequently, as in Galli, running from below upward into the maxillary sinuses. The extent of the turbinate and the richness in mucosa is probably greater in all mammals than in birds; certainly this seems true of Carnivora and Ungulata versus Accipitres and Galli.

If the seriousness of a rhinitis be dependent upon the extent of involvement of the sinuses and the blocking up of their outlets it would be expected that the variety of animal having the smallest drainage channels would show the greatest evidence of these diseases. Our records would indicate that 32 birds (.96 per cent. of the autopsies upon Aves) had rhinitis whereas only 7 mammals (.39 per cent. of autopsies on this class) presented the condition. Extension to the sinuses occurred in only one-third of each of these figures, a complication which in turn produced generalized infection more often in 136mammals than in birds as 4 is to 3. These figures are perhaps too small for conclusions but it would seem that rhinitis occurs more often in birds with their small sinuses and channels while sinusitis and general infection occur more often in mammals with their large sinuses and extensive turbinate apparatus. The most conspicuous orders represented are, in line of numbers Anseres 12, Psittaci 7, Accipitres 5, Carnivora 3. Nine of the twelve waterfowl were part of an epizoötic which will be discussed under specific diseases.

Bacteriologically the mammalian cases that have been worked out were due to Streptococcus pyogenes in several instances, including the generalized cases, and to a mixture of streptococci, golden staphylococci and members of the colon-aerogenes group. In one case in a tapir a member of the B. septicus group was found. Moulds were discovered in three avian cases and filaria in one. No pentastomum or œstrus has been discovered. In thirteen instances the lungs have been involved, apparently secondary to the nasopharyngeal disease.

There have been two small outbreaks of an acute nonspecific infection—that is not suggestive of cholera, psittacosis or infectious enteritis—among the parrots in which during a short time 4 and 6 parrots died with nasopharyngosinusitis as the prominent lesion. One outbreak was studied bacteriologically without definite result. There was no uniform internal pathology unless, in one outbreak, congestion of the cerebellum may be mentioned. Fowl diphtheria and its associated condition from which a satisfactory separation has not been accomplished, epithelioma contagiosum, has happily given us little concern, so that it is not possible to record any instructive facts upon its cause or differential diagnosis. There was recorded in the 1911 Report of the Society the occurrence of two fatal cases in cassowaries from which it was possible to isolate the B. columbarum and one bird with the same clinical appearances whose recovery seemed to be 137due to the use of human diphtheria antitoxin. In light of more information and consideration of the accepted variability of this disease, it is possible that this bird may have recovered without the injections or with the use of normal serum. Nowadays it is possible to obtain antiroup serum which is stated by Blair of New York to be efficacious. The disease has been observed in a wild turkey and an Abyssinian Ground Hornbill, beside the two struthious birds mentioned above.

Mycotic disease of the nasopharynx seldom restricts itself to this cavity, usually extending by continuity to the esophagus, or by inspiration to the lungs whence it spreads to the air sacs. This condition of the upper passages has occurred here only in Psittaci and Accipitres although it is reported by veterinarians as occurring in Anseres and Struthiones. In the first order four birds were affected, two showing extension to the esophagus and a like number having pulmonary and serous membrane involvement. These cases were all due to aspergillus whereas those next to be mentioned were caused by an oidium close to the “albicans” variety. In four Mississippi kites the prominent changes were found in the pharynx and esophagus down as far as the proventricle with only a few rather trifling lesions in the nasal area. Infiltrative and necrotizing processes characterized the action of the oidium while that exerted by the aspergillus was more superficial and extensive. In one case of a parrot the whole nasal cavity was completely filled with a yellow gray exudate whereas the esophageal wall of the kites was thoroughly infiltrated by a gray-brown, friable, necrotic mass. Attempts at treatment were made in the case of the latter, using potassium chlorate and saline solution on cotton swabs. The result was entirely negative and the applications seemed to have no effect upon the course of the infection.

138There are on our records in addition to the above, several cases of necrotizing processes about the head seeming to emanate from wounds to the mucosa by foreign bodies, by decomposition of pieces of food in crevices or by damage by masses too large to be swallowed. In the few instances where we have tried bacteriology, no definite result has been obtained unless the frequent occurrence of organisms bearing a resemblance to Bact. necrophorus be important. This organism however may be found in many necrotic processes in animals; I do not look upon it as specific in the locations just cited.

Mammals as a class do not present many inflammatory conditions around the anterior head, aside from the specific diseases like distemper (?), actinomycosis, Kangaroo disease and the like. Monkeys occasionally have acute coryza, which may indeed seem transmissible to others but it seldom leads to any serious consequences and is untreated, except by segregation. Tuberculous lesions are not recorded. There has been no glossitis aside from lesions involving the pharynx. The tonsils have been discussed under the lymphatic apparatus and it only need be repeated here that inflammation and hypertrophy of these organs are exceedingly rare. Specific or individual diseases of the salivary glands are also rare although these organs may be involved by extension. This general region is not often affected with tumor, unless the jaw be included which bone is the seat of several tumors in antelopes and opossums. Aside from these we have seen an epithelioma of the tongue in a black bear (Ursus americanus).

The larynx is an organ of fairly uniform construction through the mammalian orders but is conspicuously different in the Aves where it is double. The upper end of the trachea in the latter class is surmounted by a cartilaginous box lying beneath the root of the tongue through 139which an anteroposterior slit-like opening forms the glottis; there is no epiglottis. This is only an air passage, the voice being made in the syrinx or lower box which lies at the bifurcation of the trachea. The structure of the upper box is quite simple with its lateral plates controlled by the glossal muscles and two external retractors but the syrinx is very complicated and variable in the different orders and even in the same family. It possesses an internal and external set of muscles and in some birds can be opened at one point to permit air to pass to the cervical or thoracic air sacs. Detailed discussion of its anatomy is hardly profitable since there is nothing peculiar about its diseases. On one occasion only have we seen distinct pathological change—what was probably an extension of mould disease from it to the cervical air sac. It is involved in true tracheitis and bronchitis but even these are rare in birds.

The larynx on the other hand is constantly reddened in cases of pharyngitis and may be the seat of mould colonies. Edema of this structure is, however, not very common, it being recorded but twice in birds in association with nearby inflammation and five times in mammals; in the latter cases three were of acute infectious nature, one was a tumor and the other osteomalacia. It is common to find the laryngeal and tracheal mucosa swollen and wet in chronic bone degenerations without the condition being severe enough to call it edema.

Acute laryngitis of active catarrhal or purulent nature has been met five times in mammals and twice in birds while more chronic lesions have occurred only in the former, four times. Tuberculous laryngitis has been observed in a cockatoo and a lemur; they are interesting enough to cite. There are no cases recorded among monkeys despite the large number dying from the disease; this implies of course that no suspicion of its existence 140was had at postmortem but perhaps some would have been detected had every larynx been subjected to microscopic section. A citron-crested cockatoo was found when posted to have general miliary tuberculosis. The bright red rim of the glottis attracted attention and upon slitting open the organ, pinhead size, sharply outlined yellow tubercles were found on both sides. A black and white lemur was killed because of a positive tuberculin test. He was in good condition and exhibited as his only lesions retropharyngeal lymph nodes with precaseous miliary nodules and small miliary tubercles on the epiglottis, true and false vocal chords and in the mucosa of the main ventricle, each lesion being surrounded by a narrow sharply injected zone. This seems like a recent double implantation since the retropharyngeal glands probably do not drain toward or from the larynx. The larynx has been the seat of only one tumor, a squamous cell cancer in an Azara’s agouti. The tumor caused ulceration and edema of the whole mucosa sufficient to produce fatal asphyxia.

The trachea is of relatively little comparative or pathological interest aside from its inflammations which however are so closely associated with bronchitis that they will be included under that heading. Perhaps the most important condition of this tube is its infestation with Syngamus trachealis since this leads to inflammations not only of the related mucosa but predisposes to pulmonary infection. The occurrence in the Galli is well known but perhaps it is not so well recognized that this worm occurs also in crows (Passeres) and swans and geese (Anseres). For the diagnosis of this condition it is customarily stated that a frothy mucus in the mouth is very suggestive; this is true in the cases seen here but in addition a mucopurulent stomatitis is exceedingly common and when the two are combined the picture is almost confirmatory. Although worms are credited with considerable weight in the production of pneumonia in 141Ungulata, they have only been seen once within the tracheal tube.

The bronchi will be discussed as a separate part of the respiratory system in so far as possible since they present a very decided difference in anatomy between mammals and birds and because the incidence of their disease is other than will be found for the lungs. However, distinction has been made between changes in the grosser tubes and those in the finer bronchioles, especially because capillary bronchitis so-called is really a pneumonitis in which the mucosa of the larger passages need not participate. The mammalian tubes are not really greatly different in their construction, passing through ever smaller branchings which give an increasing square area of tube capacity and more extensive mucous surface. The avian main bronchus breaks up very shortly after entering the lung into a varying number of spaces lined with low epithelium lying upon a fibrous support and without cartilage. These spaces then open into secondary air spaces of a size visible to the naked eye which are in turn surrounded by microscopic alveoli. The largest spaces, first mentioned, continue to grow smaller toward the lower part of the lung where they usually communicate with one or other of the various ostia of air sacs. Bronchial diseases in birds must therefore be limited at the place where the bronchi lose the cartilaginous rings since below this the surface functionates as pulmonary tissue.

The accompanying list, Table 8, will show the distribution of bronchitis not accompanying pneumonia or due to mycosis. It is striking that carnivorous animals are more prone to bronchitis than any other order (the struthious birds are too few to be important). There is a very decided preponderance of mammalian cases over avian, there being not only more cases but proportionately more orders affected. The character of lesions in the mammals is nearly always catarrhopurulent or freely purulent while ulcerative changes are not uncommon. Peribronchial infiltrates are seldom found without some evidence of pneumonia; nor is it common to meet the pale lines extending from bronchi between the lobules, such as are seen in human streptococcal disease. Avian bronchitis is usually hemorrhagic or catarrhal and with exceeding rarity becoming purulent; when this occurs the cause is frequently found to be tuberculosis or mycosis. Inflammation of the larger passages is nearly always accompanied by pulmonary congestion, a serious condition in birds as will be seen later. A few of these cases have been studied bacteriologically with no definite result, nor have these cases occurred in such groups that an epizoötic was suggested. Bact. avisepticum, Bact. canisepticum, Bact. coli, Bact. aerogenes mucosum, and Ps. pyocyaneus, Streptococcus hemolyticus and non-hemolyticus and staphylococci have been found.

143A review of the active verminous lesions of the bronchi and the pneumonitis to which parasites lead, shows again the highest number among the Carnivora, with negligible percentages among the Aves. The forms concerned are, when determined, ascarides, strongylus, hepaticola, fasciolopsis, cytoleichus, pneumonyssus and paragonimus; these will be discussed later. The lesions in the bronchi are mucocatarrhal or hypertrophic; occasionally actual ulcerations are seen. What is more important however is the peribronchitis leading to interstitial pneumonitis and to bronchiectasis of the smaller bronchi, or to areas of atelectasis by total occlusion of some small air passage. This pathology is fairly well recognized among veterinary pathologists but there are two points which seem worthy of special emphasis, namely, the relative mildness of the changes in the larger bronchi and the importance of the worms as causes of pneumonia. In regard to the first it can be pointed out that the trachea and its branches need not be altered at all while the middle sized bronchi present a mottling of small recent congestion with pigmentations from old hemorrhages, together with slight unevennesses of the surface. Small bronchi on the other hand are the seat of ulcerative internal processes and quite marked peribronchitis, as indicated by round and connected tissue nuclei or perhaps polynuclear increase under active acute inflammation; it is in the latter case that acute pneumonitis is present.

144To what extent do the parasites predispose to pneumonia? Compare for this purpose the two columns of Table 8 showing active and inactive pulmonary parasitism. In Rodentia and Galli alone do we note that active parasitism is effective, there being no passive cases. In all the other orders, animal invaders of the lung are more often encountered as quiescent or encapsulated bodies, therefore as findings incidental to the autopsy and perhaps not concerned in the cause of death. In Ungulata the inactive parasitisms are five times as frequent as the active inflammatory lesions. It might be added that the list is made up of cases wherein we saw parasites whether determined or not, an explanation of the apparently small number of cases; there were many more in which such invaders were suspected but not found and therefore excluded.

Bronchiectasis affecting the smallest tubes, or bronchiolectasis, is not at all uncommon in verminous pneumonitis and is explained as due to the degeneration of the wall, the surrounding progressive ulceration, to accumulation of inspired air and its retention by the obstruction. There is described a generalized bronchiolectasis, chiefly in young human beings, due to a destructive bronchiolitis; this has not been seen.

Non-verminous bronchiectasis of the middle sized bronchi such as is seen in human chronic bronchitis, simple or tuberculous, is quite uncommon. Widening of the bronchial lumen may be divided, as I see its pathogenesis, into (a) that due to congenital weakness of the walls, (b) that due to obstruction permitting air to pass into but not out of a bronchus because of a ball-valve obstruction or weakness of expiratory power, (c) that due to external pressure by tumors or distortion by fibrous tissue either within the lung or pleura and (d) that due to inflammatory weakening of walls, augmented by loss of 145supporting pulmonary tension, accummulation of secretion and the dilating effect of inspiration preparatory to and incidental to coughing. How important the last three auxiliary factors may be in the cases explicable under a, b, c, can easily be speculated upon and may vary in different cases.

Bronchiectasis is reasonably common with pulmonary diseases of man, particularly of chronic character, but is certainly not frequent among animals. Under the first group (a) we can record one case, a Siberian tiger which died of enteritis and its complications to which were added a mild inactive bronchitis and a bronchiectasis of diffuse distribution. The lungs were irregular in shape, dull, gray-red in color and gave a variable boggy and vesicular sensation to the fingers. On opening the lung, dilatations of the bronchi were found, affecting chiefly the larger secondaries but apparently not the bronchioles. Parasites were not found nor were inflammatory reactions apparently adequate to explain the distentions, so that we looked upon this case as congenital. Cases coming under the headings b and c are not recorded. Inflammation almost certainly represents the most important single factor in the pathogenesis of this lesion and could be demonstrated in two cases, a Clouded Leopard (Felis nebulosa) and a Red River Hog (Potamochærus porcus). While I feel that parasites probably laid the foundation for the dilatations in these cases, none were found after, in one case at least, a very thorough search, although in the second animal a single cyst of Cysticercus tenuicollis was found in the peritoneum. In both animals there was a low grade interstitial pneumonitis and peribronchitis with dilatations of the middle sized and end bronchi, these being supplied with thick walls but containing very scanty secretion.

We have on record chronic ulcerative pulmonary tuberculosis in six primates, two carnivores and nine ungulates. It is highly probable that among this number 146some cases of ulcerative bronchiectasis occurred but if so they were not conspicuous enough to mention in the diagnosis and in only two protocols do I find a discussion thereof, once in a monkey and once in a carnivore. All the cases of our records were diffuse ectasias, fusiform, or irregular and none of the distinct saccular variety.

From the foregoing facts it would seem that in human cases more weight should be laid to the effect of the dilating power of coughing and its preparatory exertions. While I am aware that the comparative incidence of human and lower animal bronchiectasis cannot be based upon the meager figures at our command, these dilatations certainly can be expected in a general autopsy service more in man than in lower animals. Chronic bronchitis is relatively rare, aside from the verminous varieties. I have seen little retained exudate in the bronchi, probably because quadrupeds seem with ease to raise and swallow the secretions. Nor do animals give vent to paroxysms of coughing such as the human being feels forced to do. Suggestive deductions from these points are that inflammation is the principal factor in acquired bronchiectasis and that the retention of secretion with violent inspiratory efforts are potent in man for the dilatation of the tubes.

The essential respiratory organ of the animal body, the lung, is all through this kingdom a structure intended to expose the blood to free or combined atmosphere in order to permit gaseous interchange, therefore being arranged so that there is a close apposition of the two factors, separated only by such cells and membranes as may be necessary to protect the circulation; perhaps these anatomical elements possess at the same time some vital force to further the exchange of useful and useless matter. In the two classes under discussion there is no difference whatsoever in the primary factors of respiration albeit 147some variations exist in reference to oxygen and carbon dioxide interchange, moisture of the air, and the physics of inspiration and expiration. The chemical variables have in our limited knowledge of comparative physiology apparently little effect upon morbid anatomy but it is probable that some pathology may be in part explained on physical grounds.

The mammalian respiratory box is a relatively elastic affair, but collapsed at the end of expiration which is largely a passive or recoil process. The avian thorax is believed to be normally a tensely distended space from which air is expelled by pressure of the pectoral contraction upon the broad sternum driving the latter back upon the air sacs which in turn drives it from the lungs. Also by this means, air is distributed through the bones and air spaces, a measure necessary in flight, especially in a head wind when tracheal inspiration is said to be suspended at times. The communications of the lungs, air sacs and bones make it possible for birds to breathe internally when the trachea is closed and externally as well if a bone be opened. The balance of air pressure in the lungs and related spaces is dependent upon the patency of the ostia communicating between the bronchial ends and the air sacs, from which the bony cavities obtain their supply. Should all these be closed there is first a standstill of current and a limitation of the respiration of the lungs. Fortunately it is extremely rare that this occurs for it is obvious that it is incompatible with flight, and with life indeed. The principal effect upon the lungs of obstruction to the passages seems to be expressed in congestion but in how far this is due actually to the closure of foramina and how far to the cause of obstruction is sometimes difficult to evaluate. It should be remembered that the air sacs are usually looked upon as mucous surfaces continuous with the bronchial wall, there being a deep layer to each membrane possibly continuous with the serous membranes. In mould disease of the 148lungs there is very commonly a colony lying in the ostium supplying the anterior, lateral and posterolateral cavities.

The lungs in birds are not free as in mammals, being fitted into the troughs made by the anterior ridges of the ribs, to the serous covering of which they are lightly attached by delicate fibres running between the two. This more or less definite fixation, together with the pressure of the air in the sacs give the free play of the lungs a limited excursion. They are naturally very elastic by reason of a good supply of elastic fibers and large air spaces, a condition aided by their attachments to the supports of the diaphragm and to the insertions of the air sac walls. Notwithstanding this elasticity and the great capacity of the organ for blood, it seems as if congestion of the lungs is a very serious matter, since from the foregoing review of anatomy, accommodation of excess blood and any consolidation must be difficult. As a matter of fact the mere excess of blood known as active congestion seems able to kill small varieties.

Birds of flight seem to have little resistance to this condition and often it is the only diagnosis one can make at autopsy. The causes of this condition include exposure, dust, gorging (?), indigestion, enteritis and infection in birds while in mammals acute gastrointestinal disease stands out as the most prominent accompaniment. To what extent dust and exposure operate I do not see, although they are frequently mentioned as causes. The overfilling of the crop, esophagus and proventricle, the turgescence incident to gastric indigestion or the pressure of foreign bodies in large amount are supposed to operate by exerting pressure on the anterolateral air sacs with closure of their ostia and also by right lateral torsion of the heart with twisting of the very delicate pulmonary veins.

149I have sought to show that protozoa or embryo nematodes in the blood might embarrass the lungs to a state of congestion, a thought suggested by some findings in the London Gardens, but only about ten per cent. of our cases of hemic parasitism are accompanied by it.

The incidence of congestion of the lungs not due to stasis as from cardiac diseases, is 2.4 per cent. in mammalian autopsies, in only 7 per cent. of which figure did it represent the principal morbid anatomy, whereas in birds it occurred to the extent of 7.6 per cent. of postmortems, in 17 per cent. of which it was the sole or principal cause of death. This seems to bear out the feature of delicacy of the pulmonary vascular mechanism in these latter animals. This condition seems to be indicated by simple dyspnœa in birds, relief for which has occasionally been afforded by removal from the exhibition cages and protection separately in a warm dry room; this is partly hypothetical of course and congestion is to be looked upon as serious, particularly in passerine birds.

Pneumonia as a clinical disease is a relatively uncommon, although quite serious sporadic condition in animals. However accompanying the specific, more or less epizoötic diseases such as influenza, distemper and the choleras it may be a frequent and quite pronounced complicating feature of the case. Pneumonia per se has exacted a reasonable toll in this Garden but unfortunately recognition being impracticable, diagnosis and treatment have not progressed. Nor has it been practicable to group our cases pathologically because of the lack of history and the difficulty of making bacteriological observations at many autopsies. Fortunately we have had practically no epizoötic pneumonias, an experience shared with other gardens judging by their published reports. Etiologically, and of course this applies to non-verminous, non-mycotic and non-tuberculous cases, the pneumococcus has 150stood out prominently as a cause with a few additional cases due to the streptococcus and the Bact. aerogenes mucosum group; London reports four cases in monkeys due to the Friedlander bacillus. Some time ago Doctor Weidman subjected our pneumonias to an analysis and was able to show that there is no parallelism between the seasonal incidence of pneumonia in man and animals, rather indeed that the Garden is more apt to have a greater number of cases in the summer, a sort of “closed season” for man. This I am inclined to interpret as connected with the larger number of visitors during that season. Doctor Weidman was further able to show that the only real examples of lobar fibrinous pneumonia strictly comparable to the human infection occurred in the Primates. I have uncovered one in a lemur and one in a carnivore. The pneumococcus has been far and away the greatest producer of our pneumonias, in two typed cases being of the IV variety. There will be given below a summary of the pathological types of pneumonia encountered, to be followed by some notes upon the principal gross and minute anatomy in special orders. Table 9 will show the numerical distribution of types among the orders. All the principal mammalian orders are represented while the birds seem relatively less susceptible to the disease and, except the Passeres, show a trifling incidence.

151Primates present a definite group of variations from the other orders, notably in having four clear cases of lobar fibrinous pneumonia, and in certain histological findings. In reference to the lobar cases, a review of their history does not indicate that any might have been surely diagnosed by their symptoms, and only possibly by signs in one case during the stage of red hepatization; unfortunately no temperature records are at hand. In one case it was possible to see a group of alveoli with the fibrin collected in a strand which, according to classical description, passes through the septum to the adjoining alveolus.

There were two cases, a Chimpanzee (Pan niger) and a Galago (Galago maholi) with a microscopical picture suggestive of those we met in the influenza epidemic, and indeed the lung of the former resembles grossly the lung of influenza pneumonia. The spotty areas of watery purple color correspond under magnification to celluloedematous semisolid sections showing a sanguineous exudate, few polynuclear cells and many swollen epithelia. The microscopic picture of the bronchocatarrhal pneumonias 152shows conspicuously thickened septa decidedly wider than one is accustomed to see in human cases and apparently due more to round cell infiltration than to congestion or polynuclear increase.

Bronchopneumonia or capillary bronchitis with zones of cellular edema in the vicinity is a rather usual picture in the deaths from degenerative bone disease. It cannot be said that there is anything very peculiar about it, although a frequent note met in the autopsies describes spotty areas of hemorrhage and nearby atelectasis.

The case of lobar pneumonia found in a ring tailed lemur (Lemur catta) showed very delicate fibrinous reticulum and relatively few cells in the exudate, a picture apparently due in part to beginning resolution since the whole upper left lobe was in a stage of gray hepatization.

The peculiarity of the Carnivora seems to lie in the reaction of the epithelia, these cells being quite large, swollen and occasionally much vacuolated. Such a picture was most pronounced in the terminal bronchitic pneumonias in cases which might be called distemper. Many instances of pseudolobar catarrhal or bronchopneumonia are recorded but we also observed the fibrinous lobar form at the stage of red hepatization in a Texas skunk (Mephitis mesomelas). Concerning the orders Rodentia and Edentata no especial notes seem necessary for their inflammatory reactions are essentially like the others in that epithelial cells are much swollen and prominent.

Pneumonias of Ungulata are well known to pathology and offer in causation and microscopy little that is peculiar. It might be emphasized however that the gross appearance of the bronchocatarrhal variety closely simulates that of lobar pneumonia, therefore to be called a pseudolobar form, in that extension to various parts of a lobe seems to occur. Moreover in the bronchitic varieties associated with enteritis, with or without infectious foci in the pharynx or larynx, there may be two or even three stages of the pneumonitic process in one lung or lobe. It seems that this pseudolobar appearance occurs definitely more often in ungulates than in the other orders.

Fig. 8.—NORMAL AVIAN PRIMARY AND SECONDARY ALVEOLI. NOTE THE DELICACY OF THE SEPTAL PROLONGATIONS THAT BOUND THE PRIMARY ALVEOLI, ALL OF WHICH ARE WIDELY OPEN.

Fig. 9.—EARLY BRONCHOPNEUMONIA OF SUPERFICIAL ORIGIN. NOTE SOME LITTLE EXUDATE IN SECONDARY ALVEOLUS. WIDE SWOLLEN SEPTA AND BOTH ALVEOLI REDUCED IN SIZE.

153Marsupialia offer two rather easily grouped classes of bronchopneumonia—one associated with enteritis and one secondary to “Kangaroo disease” of the jaw; they differ in microscopy correspondingly. The simple bronchitic and peribronchitic infiltrate and superficial exudate occurring with enteritis or with a general infection is relatively diffuse, giving in some instances the impression of an interstitial process and showing notably swollen septa; there may be fibrin but this is exceptional and scanty. When mycosis of the jaw has been the origin or occasion of the infection the picture is that of frank aspiration pneumonia, therefore more like a septic infarct. However the amount of fibrin is sometimes very great and whole alveoli will be filled with it, perhaps accompanied by red cells, polynuclears and epithelia. Epithelial cells however play a small part in the minute anatomy. Hemorrhage and edema are prominent but true abscess formation and gangrene are not. Possibly the animals die too soon for the latter to develop.

Pneumonia in Aves aside from that due to moulds is apparently much less common than among the Mammalia, one order only, the Passeres, showing an incidence comparable to the important orders of the latter class. The other orders, and this applies particularly to those of which we have an adequate number, are quite insusceptible to simple pneumonia, none of them showing over two per cent. There are listed for Aves three instances of lobar fibrinous pneumonia. These cases can be described together since in all the findings were about the same. A whole lung or goodly portion thereof was uniformly involved in a red or gray consolidation of rather fine granular character which on section study seemed to be made up of the same lesion all over, with fibrin a prominent part of the exudate. The coagula were largely 154within the secondary alveoli but the primaries also contained it. The microscopic section may not have represented the process at all places, and since the arrangement of fibrin is similar in definitely catarrhal lesions, these may of course have been instances of pseudolobar pneumonia.

Our data are too few to draw any conclusions as to the behavior of the various orders but one note may be permitted. The passerine birds have a great tendency to dense cellular infiltrates while parrots show more coagulative or fluid exudates.

Insular consolidations in which catarrhal and infiltrative processes are prominent, the bronchopneumonias, seem to arise in two ways. One course of events apparently follows infection via the bronchial mucosa, the other via the blood stream and a study of the resulting lesions may help toward an understanding of the development of pneumonia in man.

When infection unquestionably has been superficial, that is via the bronchus, the first thing to happen is a swelling of the septal prolongations dividing the primary alveoli and an extension of their ends farther into the secondary alveoli with the result that the inlet to the primary air sacs is narrowed and the space in the secondaries is reduced. Upon the surfaces there then develops the usual catarrhal exudate while in the deeper parts marked congestion makes its appearance. Fibrin may develop and be mixed with the cells both in the larger and smaller alveoli but it is more evident in the former. (Figs. 8, 9, 10.)

Fig. 10.—LATER BRONCHOPNEUMONIA OF SUPERFICIAL ORIGIN. NOTE GREATER EXUDATE, GREATER SWELLING OF SEPTA. PRIMARY ALVEOLI PRACTICALLY ALL CLOSED. MUCH OF LUNG HAS BECOME CONSOLIDATED.

Fig. 11.—INSULAR PNEUMONIA, BEGINNING AS CELLULAR INFILTRATION OF DEEPER PARTS OF SEPTA AND OF INTERSTITIAL TISSUE. FOUR AREAS OF DENSE AIRLESS CONSOLIDATION. ALL SECONDARY AND MANY PRIMARY ALVEOLI WIDELY OPEN.

155The other process by which insular pneumonia develops seems to begin in the septa of the smaller alveoli and in the perivascular areas. This has been looked upon as hematogenic or pleurogenic. The first change occurs in the surroundings of the primary alveoli where there appears a richness of nuclei, of round, moderately well stained character, among which one may see a few granular and red blood cells. Soon the epithelia of adjacent alveoli increase in number and a fibrinocellular exudate appears, at first probably in the smaller sacs. However when the lesion is intensive the course of events must be rapid for the identity of a group of primary alveoli is soon lost and the exudate may extend to the larger air space. (Fig. 11) In severe or late cases a decision as to the course of origin is often impossible. The most instructive point of this part of the study is the closing of primary alveoli by the swelling of their septal ends and the early occlusion of the secondary alveolus by a catarrhofibrinous or even pus-like material. It is quite possible that a similar course of events transpires in the pathogenesis of human pneumonia, the superficial avian form being comparable to the aspiration form, the interstitial form comparable to the septicemic variety.

Abscess and gangrene of the lung are degenerative processes dependent upon embolism, or inspiration of infective matter and it is usually assumed that gangrene succeeds upon abscess when the blood or air supply of a part of the pulmonary tissue has been obstructed mechanically or by inflammation. A review of our material adds little to the etiology or pathogenesis of these two lesions, well recognized as they are by veterinarians. As opposed to human beings, lower animals probably suffer more from them, for an explanation of which one can probably look to the B. necrosis or necrophorus, an organism quite common in feed, and acknowledged to be of great importance as a secondary invader during specific infectious diseases. It has been found in embolic abscesses and in the organs in calf diphtheria and similar other conditions. It has been cultivated here twice, once from a lung abscess, once from Kangaroo disease. It doubtless occurs in human necrotizing processes but is seldom emphasized or even heard about; possibly none is due to it or its congeners.

158The distribution of abscess and gangrene in the lungs in terms of the antecedent disease, therefore its causation, may however be of interest. The lower animals move more in the horizontal position, they seldom cough, they are subject to several different diseases with principal lesions in the anterior head (diphtheria, actinomycosis, etc.) but not to chronic lymphatic infection, they push their snouts into all kinds of filth thereby probably taking into the nose and throat many objects which can find their way to the bronchi, and finally they are not subjected to various instrumental operative procedures when they chance to have a focus of pathology in the nasopharynx. For these reasons the position of abscess and its sequels may be instructive. It has recently been stated that abscesses of the lung in human beings following anesthesia for infections of the upper respiratory tract, occur most often in the upper parts of the lung whereas those following pneumonia develop more in the lower lobes. For the animals of this series, these facts are not borne out. In the accompanying list will be found our acceptable cases of abscess and gangrene. Little can be said about incidence save the fact that the highest percentage and number occur in the Carnivora. It will be found that the right lung is affected nine times predominatingly while the left lung is affected seven times. The lobe most often singled out for an isolated lesion is the lower left, the right middle being the next most often affected. These figures concern the mammals alone, the three birds being considered too few to discuss. It cannot be said from these figures that there is in animals any definite distribution of pulmonary abscess and gangrene.

Nor do these figures correspond to those appearing in literature of human pathology. In man inspiration of foreign bodies, including bacteria-laden mucus, usually 159carries them into the right lung because of the larger and more directly vertical bronchus to that side. Emboli go as a rule also to the right lung more than to the left because of the greater size of the pulmonary artery and more direct blood current to that side. In these animals right side lesions are more numerous but the left lower lobe is the principal segment of the lung to be affected. The cases are too few and the anatomy too variable to permit any deductions. There is in the affected animals no uniform anatomical peculiarity which would explain the predominance of the right lung as a whole or the left lower lobe as a unit.

Pneumonokoniosis, because of its importance in industrial diseases, has been subjected during recent years to considerable intensive study in human medicine, from which activity some interesting and useful information has been obtained as to its genesis and effect upon the function of the lung. This condition is of course a purely environmental one, the degree and particular kind of “dusting” being dependent upon the duration and nature of exposure of the particular individual. This Garden is situated beside an active railroad trunk line so that the opportunity for coal dust inhalation is continuous. The degree of anthracotic pigmentation of the lungs and related serous membranes is really negligible and with one questionable exception, we have not seen fibrosis due to this cause in any animal. The one exception, an amazon presented and living in the Garden but three months, at necropsy showed an interstitial chronic bronchitis and pneumonitis stretching out from the hilum, all of the affected area being deeply pigmented. The picture was comparable to what might be expected from a second degree anthracotic fibrosis of Landis and Pancoast. Many specimens come to autopsy with some grade 160of pigmentation, but none, except the one above, with resultant fibrosis. The degree of anthracosis is usually so slight that it has been considered important enough to include in the diagnosis but eighteen times and curiously enough seventeen of these were observed in birds. Were there more cases it might be profitable to plot their exhibition period but the use of this small number might lead to error; the average length of exhibition of the birds was about a year. It is common to observe some black specklings of the air sacs, as if pepper were dusted on them as has been said before, but even this is rarely marked. It is most often seen in the Anseres, Psittaci and Struthiones but a goodly number of cases occur in the long-lived Passeres.

The distribution of the pigment is essentially the same throughout Mammalia—peribronchial, submucous and in the lymph nodes at the root of the lung. In the birds it is first seen in the subepithelial spaces of the septa of the small alveoli where they project into the secondaries, later accumulating in the connective tissue of the main septa. Collections under the pleura and at the root of the lung are rare, the dust usually spreading out along the air passages into the air sacs.

Other forms of pneumonokoniosis are unknown. Although animals must inspire much dust from dry feed and from floors it must be caught early and removed by snorting or by the lymphatic drainage. It seems fairly well accepted that dusts are dangerous to the degree that they contain inorganic substance and as these animals are not exposed to concentrated mineral or metallic dusts, no effects are seen.

Infarctions of the lung, while not at all common, are interesting because of their incidence in the Carnivora and in the distribution. The figures concern the mammals 161only since the decision for or against infarct in the birds is very difficult because of the frequency in this class of hemorrhage with pulmonary congestion. There were eleven single or double non-septic infarcts, of which seven occurred in Carnivora, one in an ungulate, two in Primates and one in a rodent. The existence of parasites was excluded in most of the cases but could not be entirely in all. Eight of these infarcts were on the left side, five of these being in the lower lobe.

Emphysema of the atrophic and chronic vesicular types with the soft, fluffy, pigmented or pale pink organ has not occurred in the animals under observation. Acute vesicular emphysema, such as is seen in chronic bronchial and cardiac diseases, has been encountered several times. Cardiac lesions were found four times, nephritis eleven times, acute enteric conditions seven times, hepatic diseases seven times. Two cases of wide spread amyloid disease showed a deposit of this substance in the alveolar walls. It is quite common to find some grade of emphysema in monkeys dying from osteomalacia and rickets. The process is then most prominent in the upper lobes and along the free anterior margins. The incidence in the orders is Primates 5, Lemures 2, Carnivora 2, Pinnipedia (drowning) 1, Rodentia 1, Ungulata 4, Marsupialia 4. The best example was found in a Skunk (Mephitis mesomelas) having a general infection, emanating from the cranial sinuses, and cardiac dilatation. Emphysema does not seem to occur in birds for only one was seen which seemed to present this condition. This was a Bald Eagle (Haliæetus leucocephalus) with chronic renal and enteric disease and cardiac hypertrophy. The lungs were tensely distended under their serous covering and showed a few small bullæ anteriorly. Unfortunately a histological preparation is not at hand.

Tumors of the lung are moderately common, both of primary and secondary origin. Thus we have seen three primary and six metastatic growths in mammals and one of each kind in birds. The primaries were: carcinomata in a civet (Viverra tangalunga), a bandicoot (Thylacomys lagotis), a kangaroo (Macropus rufus), and a lorikeet (Glossopsittacus concinnus). The secondaries were: carcinomata in a black bear (Ursus americanus), a polar bear (Ursus maritimus), a lion (Felis leo), and a dasyure (Dasyurus maculatus); sarcomata in a prairie wolf (Canis latrans), and a raccoon-like dog (Canis procyonoides); adenocarcinoma in a chestnut-eared finch (Amadina castanotis).

The histological character of the primary cancers would place them in group of the nodular and infiltrative types of Kauffman. They all seem to have taken their origin from the smaller bronchi, the usual starting point. The growths were small in the civet and bandicoot and strongly suggest that the tumors arose in bronchi occupied by parasites; such bodies could not be demonstrated. It is the usual thing to find in cases of parasitism of the bronchi that if there be no ulcerative destruction of tissue the epithelium undergoes some form of hyperplasia, and even structural metaplasia in the air tubes supplied with cuboidal or cylindrical cells. Epithelia many layers deep have been encountered, usually arranged in orderly fashion but frequently “papillomatoid,” suggesting the epidermal layers yet not so far as to show protoplasmic bridges. Distention of various degrees, affected by the contents of the tube and the surrounding inflammation, are common. Such a picture naturally resembles epithelioma and indeed growths of this nature are reported as due to verminous pneumonitis.

There are, especially in cats and dogs, small scattered adenomatoid growths^[21] under the pleura and in the 163pulmonary substance, thought to originate in the alveolar epithelium and occasionally growing to large size; the case in the kangaroo may have had this origin. It was the only primary tumor to give metastasis (to the spleen and gastric wall), the secondaries being decidedly adenomatous in character.

Metastatic growths come from the following originals: two from the thyroid, well known to give pulmonary embolism in dogs; one each from the breast, uterus, adrenal, intestine and kidney. The form assumed is a gray and red mass lying under the pleura or an isolated nodule in the substance. Sarcomatosis, the form apparently spreading out from the hilum and growing in isolated grayish tubercular masses, has not been seen.

The pleura is a tissue apparently quite susceptible to infection in mammals and so closely associated with the air sacs in birds as to be a part of the same membrane, therefore the two being affected together. Throughout the higher class all orders give copious examples of the involvement of the pleura, principally of course as an accompaniment or a sequel to pneumonitic or bronchitic processes but also as a part of acute infectious diseases, such as hemorrhagic septicemia, pleuropneumonia and the like. However two orders present such a number of instances of pleuritis that they deserve notice. The seals, Pinnipedia, of which we have twenty autopsy records, showed inflammation of this membrane four times, three of which were dependent upon pulmonary infection and one apparently due to general septicemia with trifling damage to the lung proper. One of the first cases had gone on to empyema of the classical type, a shrivelled dry almost carnified lung with a thick fibrinopurulent covering. The lung of the seal is well divided into lobules, the external surface being generously supplied with lymphatic channels under the pleura, an arrangement which 164should carry away infection one would think. Perhaps this high percentage of pleurisy in our Pinnipedia is but accidental. The marsupials, while having a notable percentage of pleurisy both among all the cases and in relation to the number of postmortems, are not so striking from the etiological standpoint since practically all of these have suffered with Kangaroo mycosis or pneumonia. In over half the cases of this infectious disease some grade of pleuritic exudate has been observed, only one, however, going to the stage of empyema.

One cannot speak so definitely of pleuritis in birds since this tissue merely represents in them the covering of the lung and is firmly attached posteriorly to the ribs and anteriorly to the air sacs. Exudates show as collections upon the air sac side of the combined membrane, pleuritis proper in birds being an infiltrative affair coming through the pulmonary tissue and therefore being a part of pneumonitis. I notice a tendency in a few articles to write of pleuritis when the process is confined to the thorax but this gives the impression that the disease is peculiar. There seems no difference in the gross and minute appearance between thoracic serositis and panserositis. The course of procedure seems to be from the anterior or mesial pulmonary ostia into respectively the cervical and thoracic air sacs and this seems to hold good whether the infection be mycosis or fowl cholera or fowl pest. There are records of 104 cases of serositis in birds of which 45 were among parrots, the remainder being well distributed among the various orders; only two each occurred in Galli and Anseres, orders prominently affected under domestication. This high percentage of pleuroperitonitis among parrots and their congeners can only be explained upon the ground of a continued infection of our stock by the virus of fowl cholera and by mould. One case of undoubted fowl cholera occurred recently and as the records are reviewed a few are discovered where the organism was found. The virus must be of low grade for we have had no severe and devasting epizoötic. Mycosis is constantly with us no matter what we do in hygienic measures. There was a small group of cases of pulmonary and serous membrane mycosis combined with staphylococcus infection which carried off six birds. The pathology of this group was interesting because one could follow the infection of the bacterium. The anterior pulmonary ostium was surrounded or covered by a mycotic mass and spreading downward from this was a grayish yellow turbidity of the air sac walls with a delicate sticky or almost mucilaginous exudate extending into the lateral abdominal and posterior sacs.

Fig. 12.—ENDOTHELIOMA OF PLEURA. LEOPARD (FELIS NEBULOSA).

Fig. 13.—ENDOTHELIOMA OF PLEURA IN FIG. 12. DETAIL OF ONE OF THE WARTY EXCRESCENCES.

165There is on record one tumor of the pleura, an endothelioma, in a Clouded Leopard (Felis nebulosa). It was the usual plate-like thickening with warty excrescences. No metastases occurred. (Figs. 12 and 13).

SECTION VII THE ALIMENTARY TRACT. PART 1.—PHARYNX, ESOPHAGUS, STOMACH AND INTESTINES — Pharynx. — Dilatations of Esophagus. — The Proventricle. — The Stomach. — Gastric Ulcers. — Tumors. — The Intestine. — Inflammation. — The Table. — Mammalia. — Carnivora. — Marsupialia. — Aves. — Gastritis. — Enteritis. — Constipation. — Mechanical Obstruction. — Ileus. — Hernia. — Rectal Prolapse. — Diverticula. — Tumors.

The portion of the anatomy that we now approach varies in construction almost as much through the animal kingdom as do the external shape and covering of the various orders and much more than do the other systems. The reason for this is obvious, an arrangement accommodative to the differing food chiefly, but not a little to the ease with which animals obtain and assimilate their nutriment. It would be impracticable to describe all the variations of the orders discussed in this study, but since certain gross and minute differences are of importance in comparative pathology they will be discussed at the appropriate places. It is my purpose to present in a subsequent section a discussion of food in captivity from the standpoint of its quality and quantity in relation to pathology.

Doubtless the quality of food is the largest factor in the production of disease both of the alimentary tract and elsewhere, but I am not at all sure that the quantity may not be equally important, in certain groups at least. Thus, for example, the ungulate has nearly always available in bedding a substance that he can and will eat, and the prevalent idea that an animal will eat only as much as is good for him seems not to hold at all times, since overfilled rumens are only too common. It might be thought, however, that captivity creates a sort of pica, or that enforced idleness is conducive to gorging. The use a few lines above of the word “doubtless” may have arrested the attention of some, yet when the whole subject is reviewed it seems entirely justified. Plimmer puts incorrect food at the head of the list of the causes of enteritis, 167Brooks emphasizes the importance of certain grasses and musty fodder, systematic writers detail among the principal causes of gastritis spoiled food, and in zoological gardens specific disease like hog cholera and enterohepatitis are relatively uncommon while nonspecific gastroenteritis is the most frequent diagnosis in causes of death.

The other factors to which enteritis is ascribed are animal and vegetable parasites and mechanically operative foreign bodies, the last being unimportant. Just how important the first mentioned are is a matter of some question which must be subjected to considerable study before any solution can be expected.

If for no other reason than that the gross and minute pathological anatomy of gastroenterocolitis is the same through the mammals and birds (aside from a few specific lesions like enterohepatitis, typhoid fever, etc.), while the food and bacteria vary, it would seem probable that the ultimate cause is the same, a poison which can be formed alike in the carnivorous and herbivorous gut, and not dependent upon bacteria, but upon the chemistry of the food or of the intestinal mucosa. To put the matter more simply, the lesions being the same under nearly all conditions is not the cause the same, and is it not a poisonous product from food or the intestinal lining. It is profitable here only to mention the marked similarity of enteric lesions under the differing conditions and in different orders. We shall study chartwise, the various forms of inflammation from the cardia to the anus in terms of their anatomical diagnosis and most probable etiology in an attempt to throw light upon the matter, and later present the physiology. System requires, however, some attention first to anatomical order so that a brief review of the esophageal and pharyngeal conditions is indicated.

The buccal-pharyngeal cavity in mammals is used chiefly as a passage way for food and as the place where some of them triturate and insalivate the bolus. Certain orders, Primates, rodents and marsupials, use this cavity thoroughly at the first mastication, others use it little at first but may ruminate, the ungulates, while strict carnivores use it very little. The Aves use their pharynx almost exclusively as a passage, and, despite the presence of a certain amount of salivary gland tissue, probably do not digest any substance in this cavity. The crop or ingluvies is a sac to permit of salivary digestion but is really a storehouse to allow rapid feeding without overfilling of the proventricle. The esophagus extends from the pharynx to the cardiac opening of the stomach in mammals and widens into the glandular stomach or proventricle in birds, the upper end of which lies in front of the lower third of the left lung behind the heart.

Inflammations of the buccal, pharyngeal and esophageal walls are relatively common in certain orders especially ground birds and grazing ungulates. This would seem to be explained on the basis of injury to the mucosa by sharp or pointed objects picked up while feeding. The character is usually necrotizing, but need not be, and the bacteriology is not specific. Definite infectious diseases like diphtheria and actinomycosis are not included here, but it might be mentioned that the second disease cited is believed to be started by the penetration of the organisms into wounds made by sharp grasses. Certain orders, notably Ungulata, Passeres, Psittaci and Struthiones, are quite susceptible to mycotic infestation and we have seen an outbreak of thrush in Kites (Accipitres). It is, however, interesting and possibly significant of peculiar protective powers in the upper alimentary tract, that strict carnivores have failed to show ulcerative, purulent or necrotizing inflammations of the mucosa from the 169mouth to the cardia. There has been no important data upon ingluveal indigestion or esophageal obstruction. Birds especially, and occasionally mammals, gorge themselves or take too large a bolus, but it seems as if this is only fatal where some distinct important pathology is present which has reduced their resistance. In the lower esophagus one has to deal with worms in connection with the proventricle in birds, but no mammals seem to have suffered with temporary or permanent strictures. “Crop-binding” has occurred in the following orders: Psittaci, Galli; and overfilling of the esophageal dilatation was seen in Accipitres and Herodiones; Columbidæ with their double crop were not affected by this abnormal collection of food in the esophagus.

The mammals have shown three dilatations of the esophagus interesting enough to detail briefly:

Mongoose Lemur (Lemur mongoz) ♂ . Sacculo-fusiform dilatation of esophagus, probably congenital, with adjacent fibrosis of lung. In poor condition for several years but recovered satisfactorily from a bad cut inflicted by cage-mates. At autopsy the general condition is poor, hair missing in spots, all skin dry and atrophic with patches of keratotic dermatitis. All tissues anemic, muscles lusterless. Right lung collapsed, brown and pink, spotted with anthracosis. Left lung pushed forward and to left by a mass in the posterior mediastinum. Lower lobe in its posterior portion is adherent to esophageal mass. Lower half of this lobe beginning where bronchus ends and extending over anterior-posterior surfaces shows marked fibrotic processes and at one point in tissue between end of bronchus and adherent esophagus there is no lung tissue remaining. No recent consolidations. Bronchial lymph nodes, small, firm homogeneous pale brown with specks of anthracosis. Heart contracted, normal in size, firm red-brown. Aorta is firmly adherent to esophageal mass where bronchus crosses it. The lower half of the esophageal from the hilum of the lung to the cardia is the seat of a dilatation, fusiform for the most part, but with a saccular portion anteriorly. This latter presses the left bronchus upward and heart forward. The wall of the tube is slightly irregularly thickened but there is no cicatrix and mucosa shows slight hypertrophic condition. A large mass of food occupies the dilatation. Stomach is empty save for gas. Mucosa is soft, smooth, pale pink. Duodenum shows 170slight swelling of the rather pale yellow submucosa and mucosa, but the tips of the villi are injected. Intestine contains only a little slimy mucus. Large intestine contains a mass of constipated feces. The esophageal dilatation seems to have been congenital although it is barely possible that the fibrosing pneumonitis and pleuritis may have aided and caused it by traction. It has been doubtless the cause of the animal’s inanition.

Black Bear ♂ (Ursus americanus). Sacculate dilatation of esophagus with chronic esophagitis. Chronic hypertrophic gastritis. Chronic lymphadenitis. Fatty degeneration of liver. Acute catarrhal enteritis. Had been vomiting more or less, nearly every day for two months and did not eat for six days before death. Mouth, pharynx and esophagus are full of macerated, unrecognizable food. Pharynx seems normal. Larynx is yellow, mucosa rough and slightly thickened in places especially just above the vocal chords. No excess of mucus. Esophagus in neck is dilated. Mucosa is rough, irregular yellow brown. This dilatation proceeds downward so that at thoracic opening tube is twice normal size. Upon entering thorax this dilatation turns to right and in irregular saccular form extends to diaphragm compressing heart and lungs to left. The main course of it then recrosses the midline, aorta being slightly twisted as it regains position in front of vertebræ. The wall is irregularly thickened from pseudomembranous patches and some hypertrophy of mucous and submucous layers. Muscle and serous coats are considerably thinned. The sac is full of macerated food and gas. The right lung is compressed small resilient red gray. No adhesions in either pleura. On section the lung tissue is found to be slightly edematous, red gray, compact and while not atelectatic yet crepitates much less than normal. Left lung is the seat of passive congestion in lower lobe and lower half of upper lobe. The upper half of lobe is compressed and subcrepitant like the right lung. Lymph glands of neck and thorax are much enlarged firm with large irregular, clear outlined follicles and brown firm homogeneous pulp. The aorta shows slight roughening, the intima being smooth and homogeneous.

Lion ♂ (Felis leo). Ten and one-half months old. Cystic parenchymatous goitre, dilatation of esophagus, ulcerative enteritis. Acute glomerular nephritis. Chronic hyperplasia of spleen. Fatty infiltration of liver. Bronchopneumonia (from pressure of goitre). Ascaris in intestines. Had lump on neck for several weeks, ate very little and seemed to have hard work to get anything down. Stopped eating toward the last and vomited water and foam. There is a small ulcer with everted lips just below left incisor on lower lip which the keeper says is of several months’ duration. The thyroid is much enlarged and forms a large mass in the upper chest and extends far up in the neck. Because of this mass the lungs are pushed far down in the chest. Heart also lies very low. The thyroids are enormously enlarged and cystic, the right measuring 13 × 8.5 × 5 cm. and the left 19 × 9 × 5 cm. The lungs are pale pinkish white. Air content increased in places, decreased in others. No hypostatic congestion. The lungs seem normal except at the apex where they are collapsed probably from pressure on lung by enlarged thyroid which dips down into the chest for at least three inches filling entirely the apex of the chest. One bronchial lymph gland was about the size of a walnut, the rest were normal. The heart seems normal except for its slightly low position. The abdomen contains about 300 c.c. of deep yellow highly albuminous fluid. No adhesions. The liver is softer than normal, glistening, smooth, moist and very yellow particularly at the edges. The gall-bladder contains a green mucoid bile and the duct is patulous. Spleen and kidneys are normal. Mouth and pharynx are normal. The esophagus is much dilated above the thyroid. The enlarged thyroid pressing upon it, has acted as a distinct obstruction. In this pouch was a large amount of food probably (from the history) eaten two days before. The esophagus below this point was normal except for the presence of thin mucus. Stomach empty save for two small bits of meat. The duodenal walls are much thickened, mucosa covered with small ulcers many with a hemorrhagic base; there were present also a few small, round worms.

Fig. 14.—DILATATION OF ESOPHAGUS. LION (FELIS LEO). DILATATION PROBABLY DUE TO OBSTRUCTION BY ENLARGED THYROID BODY. IN ILLUSTRATION DISTENTION OF ESOPHAGUS CAN BE SEEN IN THE FORK OF THE THYROID LOBES.

171Here are presented three different dilatations, the first probably congenitally started and aided by pulmonary fibrosis, therefore secondarily a traction diverticulum, the second probably entirely congenital, and the unusual third case due to obstruction by an enlarged thyroid. In this connection might be mentioned small saccular diverticula in the proventricle of a Fire Finch (Lagonosticta senegala), and at the pylorus in a Puma (Felis concolor). Neither of these seemed of any significance and played no part in the death of the animals; they did not seem to be artificially produced, by worms, for example.

The proventricle or forestomach of birds, is the seat of active secretion of the gastric juice in nearly all orders, although Jobert believes that the mucosa of the gizzard may contribute some digestive fluid, and there are active glands in this tissue in a few orders. The proventricle does not act as a reservoir during digestion, but as soon as the juices are well mixed with the bolus the food is 172passed on to the gizzard. The organ has a rather free position, at least as far as its left lateral and downward movements are concerned for the left lateral abdominal air sac is free on that side of the gastric complex and the left lateral thoracic also extends down the side of the proventricle. Upward and anteriorly is the heart. Some of the cases of proventricular spiropteriasis have shown very marked congestion of the left lung, possibly due to the closure of the anteroinferior air sac aperture on that side. Aside from parasitism, affections of this organ are not very numerous.

Infestation with spiroptera and with less dangerous worms was quite serious at one time, but since routine examinations of all suspicious birds has been practiced this parasitism has been under control. This is a subject of especial importance to collections, and will be described in a special section. The susceptibility of the proventricle to damage seems from our figures to be very distinctly a matter of zoological order. In so far as parasites are concerned, the parrot group stands away ahead of all others having an incidence among autopsies upon Psittaci of 16 per cent.; after them come the Picariæ with 9 per cent., and Columbæ and Passeres each with 4 per cent. When, however, non-verminous conditions are reviewed the anserine birds are found the most susceptible, 3 per cent. of the autopsies upon this order revealing proventricular lesions; after them come the Columbæ, 2 per cent., and Psittaci, 1.5 per cent. In this group are included inflammations of all kinds, dilatations and distentions and some lesser matters.

This part of the stomach has been involved in our cases of fowl diphtheria, showing a distinct mucopurulent inflammation with penetration into the depths of the glands; no separation of the mucosa occurred, but ulceration was seen. Perforation was observed thrice, twice by ulceration around a worm while it was boring into the 173muscular layer and once, in an ostrich, by the penetration of a nail. Obstruction of this division of the stomach by impaction of food and stones is not common, but does occur. The reason for such obstruction is usually very obscure. Sometimes it seems due to the feeding of seeds and the like in too finely divided form, whereby food and pebbles are taken up together. Some of the smaller birds have had in times past too many small pebbles in the cages, while others have had too large seeds, thus apparently trying to use the pebbles to crush them. It would seem also that the birds had really eaten too much and could not accommodate it in the gullet and gizzard; this seems surely true in three or four Accipitres. Most often, however, we have had to fall back upon the inadequate explanation of pica or perverted appetite.

Impacted proventricles and gizzards have been observed thirty-four times, in eight of which it seemed the sole cause of death, and therefore probably entirely due to foreign bodies in food. The theory is accepted that dilatation and obstruction will not occur if the motor power of the gastric wall be normal and no inflammation exist. In this regard we can only discover five birds (the mammals will be discussed later) with any distinct inflammatory or degenerative disease of this part of the anatomy and two with lesions elsewhere which might affect the musculature; this leaves the vast majority of gastric obstruction in birds unexplained on basis of defective motor power, therefore probably dependent upon the character of material consumed. The anserine birds and parrots are most often affected by this form of obstruction.

Acute or chronic dilatation of the forestomach and gizzard is very rare in birds, it having occurred only thrice in our records, a finch, a parrot and an owl; the causes were entirely unknown since the cavities were not overfilled with food.

Impaction of the mammalian stomach is a diagnosis made but once in our records, an Indian Antelope (Antilope cervicapra), and this is viewed with suspicion. The rumen was undoubtedly tightly packed, being distended to its fullest capacity with rather dry and not properly softened grain. However, postmortem changes had advanced and therefore observations in the whole body were not dependable. The bulk of food which can be accommodated by the rumen is very large, and had this not been dry and firm the condition might not have been interpreted so seriously. Many animals come to autopsy with a well filled, indeed even with a well packed stomach, but there is usually sufficient reason for this or there is distinct pathology to account for death.

All this of course implies a stomach of normal or approximately normal dimensions since distention beyond this, or dilatation of the stomach, is more definite. In veterinary medicine, gastric tympanites (rumen alone or all stomachs, or the simple stomach) is ascribed to food that ferments easily when taken in excess or in the presence of defective motor power, to constrictions by scars and to obstructive tumors; excessive feeding is sometimes mentioned but given a subordinate rôle. Our records throw very little light upon the subject since only five cases were observed. Four of these five seem to be due to acute fermentation independent of gross physical obstruction, while one, a Cape Hunting Dog (Lycaon pictus) showed an old chronic ulcerative gastritis with both healed and active ulcers distorting the pyloric end of the organ. Three of the first mentioned four were monkeys and one was an ocelot. The stomach of the voracious monkey is at time of dissection usually well filled, but in these cases there seems no doubt that gas and excess fluid had distended the cavity enormously, in one instance apparently assisting in acute cardiac dilatation. There were no obvious reasons for assuming any damage to the gastric motor mechanism.

Fig. 15.—ROUND ULCERS IN STOMACH WALL. COMMON OPOSSUM (DIDELPHYS VIRGINIANUS). THERE IS GENERAL MODERATE CHRONIC GASTRITIS WITH ROUND ULCERS NEAR THE CARDIA.

Gastric ulcer, so-called peptic or round ulcer of the stomach, having a chronic course and leading to radiating scars of the mucosa is not common in the lower animals, but frequent enough in the human being. The form of ulcer in question has at present no adequate explanation, or at least there is no one cause which will answer for all cases. Local injuries from within or without the stomach, bacterial embolism, entrance of bile through the open pylorus and many other factors have been named in the causation but can seldom be used in any given case. In the lower animals with their relatively frequent parasitic infestation, another factor is added. In analysis of our statistics I have separated ulcerative gastritis from parasitic and mycotic ulcerations and from peptic ulcers; the first is discussed in later paragraphs. Parasitic ulcers of the stomach occur chiefly in our native marsupial, the opossum, and in some Carnivora; physaloptera, strongylus, ascaris, and gastrophilus have been found. The kangaroos are frequently affected (8 cases) with an acute or subacute ulceration of the gastric wall, without much general gastritis. The lesion is peculiar in appearance. The youngest ulcers are black or dark gray, flat necroses of the mucosa alone and indeed the process very frequently penetrates no deeper. Older lesions spread laterally and may be preceded by a very narrow congested line but there is no raised edge nor does there seem to be submucous infiltration. If the process be rapid a loose dirty slough may form. Certain of the advanced cases of Kangaroo mycosis will present more infiltrative lesions of the gastric wall leading to large and well defined necrotic areas; they may at times penetrate the whole wall outward. (See page 580.)

176True peptic ulcers have been found in Primates, 4; Carnivora, 5; Pinnipedia, 2; Insectivora, Ungulata and Hyraces each one. The London Garden reports that gastric ulcerations occur most often in Carnivora and Marsupialia. Those in the last three orders of our list were small, usually multiple and relatively superficial. The ulcers found in Primates and Carnivora present the usual pictures seen in man. In one example in each of these orders radiating scars of healed defects are mentioned in the notes. None of them seems to have led to cancer, and in only one, a wolf (Canis lupus), was the scar tissue sufficient to cause definite impediment to the motility of the stomach. Six of the fourteen examples appeared on the greater curvature, the remainder on the lesser. Ten ulcers were in the pyloric division, the other four being scattered. No other pathology is found common to these cases which might be drawn into etiological association.

Tumors of the gastric complex are not at all common, there being only the following to report: Primates, Hamadryas Baboon (Papio hamadryas), diffuse adenoma; (none in Carnivora with the most ulcers); Marsupialia, Red Kangaroo (Macropus rufus), malignant papilloma with metastases. The former tumor, shown in Fig. 17, was a diffuse soft excrescence beginning near the pylorus and stretching along the lesser curvature toward the cardia. Histologically it was made up of glandular acini growing in all directions but always maintaining normal relations of cells and basement membrane. There were no metastases and other reasons for death existed. The tumor of the kangaroo stomach was a true epitheliomatous cancer with metastases to liver, spleen, and kidney. Only one secondary tumor was observed, from a carcinoma of the lung in a Red Kangaroo (Macropus rufus).

Fig. 16.—MULTIPLE GASTRIC ULCERS. COMMON WOLF (CANIS LUPUS). CHRONIC GASTRITIS WITH NUMEROUS IRREGULAR ULCERS OF THE PEPTIC TYPE.

Fig. 17.—PAPILLOMA OF STOMACH. HAMADRYAS BABOON (PAPIO HAMADRYAS).

Inflammation of the gastrointestinocolic tube is the most important single condition with which handlers of animals have to deal, and unfortunately it can seldom be diagnosed clinically, early and accurately enough, to make treatment useful. At this Garden some evidence of acute or chronic disease of the tube has been present in 31 per cent. of our autopsies. The reports of other gardens would indicate that their figures might be quite close to this. What is the cause of this high mortality? Incorrect feeding, qualitatively or quantitatively has been put at the top of the list by Plimmer, but he adds other less important factors: Bacteria of infectious power, protozoa, foreign bodies and parasites or their mural cysts. In order to evaluate approximately how each of these acts let us review the causes as they are generally known and later discuss the pathology as seen in the various orders.

(1) Overloading of the stomach by too much food or by rapid eating of a hungry animal is of importance under certain domestic circumstances where times of feeding are irregular or intervals are too long, but this cannot occur in any well regulated menagerie. It is possible, however, that overfilling might occur in certain Ungulata, which have hay and straw nearly always available, if the food in their reach happens to be particularly agreeable or tasty to them.

(2) Insufficient mastication would seem to be important only in those orders which depend upon this action to triturate, insalivate and macerate their food, of which Homo, Primates, Ungulata and Marsupialia are the principal ones.

(3) Disturbance during and after feeding has always been believed to affect digestion unfavorably, and it may be that visitors to a collection exert such an effect; this factor is probably negligible.

178(4) The appropriateness of the food is a very important factor in the health of an animal under captive conditions. Diet lists are made up by officials largely according to the known habits and general physiology of an animal, but the food offered can at best only approximate what the wild beast obtains for himself. It does not follow because a selected diet may seem to provide all the elements contained in the food available under natural conditions that it actually does so, especially since we are aware that some essential food factors, known under the term vitamins, are necessary to best development. These substances vary in closely similar foods, and seem to be higher in simple natural foods than in prepared diets. We have seen in this Garden that the inorganic constituents must be correctly represented in the food, else degenerative osseous condition may develop. Inappropriate diet may express itself at once after the receipt of an animal, by its sickness or death, or after some time in the development of chronic tympanites, chronic intestinal catarrh or bony deformities.

(5) The physical condition of food is a matter of no small moment. The taking of soft food in large quantities especially by herbivorous animals, permits too short a sojourn in the gastric fundus and is often followed by pyloric and duodenal disease. Too firm food may pack the rumen, fundus or proventricle as the case may be, and be succeeded by distention of these parts and catarrh of the pyloric and intestinal area. The effect of foreign bodies mixed with food is difficult to evaluate unless of course they be of such a nature (pointed metal and the like) as directly to traumatize the mucosa. Many birds and mammals come to autopsy with a relatively large number of stones and small sticks in the stomach without any distinct evidence that they have been hurt thereby. In the bird the stones may be so large and numerous as to leave little room for food, or small enough to pass out into the intestine where they undoubtedly may pave the way 179for bacterial action. Smoothly polished pebbles in small quantity seem to have little effect in mammals. Hair balls are not common and unless of large size are apparently unimportant. Considerable sand mixed with food has a distinctly irritating effect. It is perhaps best known as a chronic gastric disorder of horses; we have seen it in zebra.

(6) Spoiled food is obviously a very prime factor in inflammations of the gastrointestinal tract. Its operations are illy understood except perhaps when products of fermentation or putrefaction prevent digestive action or are absorbed. If in small quantities not sufficient to cause acute fermentative inflammation or intoxication, such substances frequently taken may doubtless produce chronic catarrhs. Many animals are fed upon vegetable mashes, or stews which can decompose, while bad meat may occasionally be fed. We had a rather serious outbreak of enteritis in small Carnivora from the use of fowl heads obtained at hotels; some of these cases were shown to be due to B. paracoli, thus to be looked upon as infections. Dirty food while not spoiled may carry with it organisms of decomposition, or of infective qualities, or the dirt may act as an irritative foreign body. We have found that for delicate ungulates (antelopes) it is highly desirable to screen grain, and that the grade of hay should be of the best.

(7) Infectious conditions are of great importance under certain circumstances but with the exception of hog and fowl cholera, the dysenteries and a few other diseases, do not as a rule play a great part in mortality as specific diseases unless of course an epizoötic appear. The greater problem is to understand bacterial action in the face of other factors. Are infectious germs introduced with food and drink in every case of gastroenteritis or do some other factors activate those already present in the gut tract? Unfortunately these questions cannot be answered directly. We can, however, point out which 180groups of bacteria are most common in some of the orders, which orders are most susceptible to bacterial invasion and which to local lesions with intoxication. The greatest problem in the field is the interrelation of germs of various sorts in the intestinal tract. Certain varieties are known to develop intoxicating aromatic substances, others to elaborate or excrete fatty acids, still others to form antiferments but the conditions existing in the various kinds of intestinal tracts are too little understood to help very much in this study.

(8) Animal parasites have long been considered as one of the causes of gastrointestinal inflammation, a condition largely due to copying from book to book of a few facts and more impressions. The sum of reliable information to-day would seem to indicate that a few parasites—uncinaria being the most conspicuous example of this type—draw considerable blood from the mucosa, that a few, like uncinaria and dibothriocephalus, elaborate an absorbable toxin, that some, notably ascarids, produce an irritating substance, and that many possess the power in themselves or by some excretion to act as antiferments. These factors, were they all combined in one worm, might probably irritate the mucosa sufficiently to produce inflammation, but it is not easy to imagine that they would cause an acute specific condition. It is much more easily conceived that with tiny hemorrhages or ulcerations of mucosæ, bacteria might get in their work or if considerable ferment were neutralized, maldigestion, flatulence or indigestive irritation would ensue. With certain worms like esophagostomum there is considerable evidence to show that a chronic fibrous disease of the intestinal wall arises, but in this case the parasite resides in the mucosa and acts as a foreign body. It would seem, however, that the most important influence that animal parasites exert is to be found in the preparation of the mucosa for the action of bacteria. Masses of parasites may of course 181physically obstruct the lumen and lead to intestinal stasis and dilatation.

In analyzing the cause of a gastroenteritis and its consequent effect upon the wall of the tube and upon the viscera, certain physical, chemical and physiological factors must be considered. Whether this may be directly the effect of bacteria or poisons from worms or some other factor seems of little moment since in any fully developed case, symptoms and effects are comparable. Moreover it seems that pathological anatomy, both gross and minute, is essentially the same from Primates to struthious birds, the highest and lowest of the two classes here considered. By this is meant that the acute congestive condition of the gut tract with solution of the surface, to which we have applied the name of toxic enteritis, seems to be met with in this form throughout all the orders. So too catarrhal inflammations are the same to the naked eye and under the microscope, due allowance being made for the fact that mammals use polynuclear cells for exudative purposes while birds employ mononuclears. Concomitantly with these conditions, a degenerative process may be going on in the liver and kidney, and hyperplasias, especially in the true infective processes, will be found in the related lymphatic structures.

The majority of students to-day place responsibility for gastroenteritis upon the bacteria known to be present in the various intestinal tracts, mentioning especially colon and proteus groups, streptococci, the necrosis bacillus and anaerobes of the Welch class. In a few of our studies of intestinal bacteria in cases of enteritis one thing has been very definite and that is that in the intestinal content of animals whose food is largely meat, Gram-negative bacilli have predominated, whereas in herbivorous animals Gram-positive organisms have been most numerous. From the observations of Kitt, Strassberger and some others, the normal flora of domesticated animals is subject to wide variations so that our observations must receive confirmation before they are finally acceptable. We have on several occasions isolated from carnivorous intestines Bact. paracoli, Bact. suipestifer and other members of this group. We have no reliable cultural data upon the herbivorous intestine and can only quote the Gram pictures as mentioned above. On two occasions, an eland and an elk, a very large number of forms corresponding to necrosis bacillus were seen; to this organism Kitt gives considerable power in the production of necrotizing processes.

Our records have been analyzed from the standpoint of diagnosis and the most probable cause. The first will be taken up in discussing each of the orders. The probable causes are divided into food, bacteria, animal parasites, physical objects and undecided, in other words a classification based upon the most prominent or definite evidences as seen at postmortem combined when possible with antemortem observations. When findings were inconclusive or contradictory, cases were called undecided, naturally a very large group. Fermentative processes in the presence of obviously undigestible material, are classified with food as a cause. When evidences of septicemia existed in absence of the other factors, it is held that bacteria were responsible. Cases were grouped under animal parasites when these were the most definite findings. Physical objects are relatively unimportant and self-explanatory. To the etiological chart there are appended columns intended to show the percentage or case incidence of the disease of the grosser subdivisions of the gastrointestinal tract which indicate in a general manner what part of the tube in the various orders is most susceptible to disease. While of course 185conclusions must be drawn with great caution, there can be little doubt, for example, that carnivores and marsupials have more gastric disease than any other order, and that the high place for the colon is held by the gallinaceous birds. This charting was suggested by the work of Dr. Raymond Pearl upon statistics, wherein he takes as a basis of classification the part of the body which succumbs to disease-producing organisms or from which a disease starts. It cannot be stated that there is a clear cut relationship between enteritis and the expectancy of life.

The Primates as an order have their share of inflammations of the gastrointestinal tract and present points of interest. Acute digestive disorders succeeded by acute dilatation of the stomach, or in less fermentative cases by acute catarrh of the intestine, are not at all uncommon. The reason for this is not discovered by reviewing the diet and manner of feeding. The buccal pouches, distensible esophagus, the freely movable stomach, and relatively elastic gastric wall would seem to permit of very considerable dilatation to accommodate the large quantities which the monkey sometimes crams into himself. Nine fairly acceptable records of gastric overfilling exist and two of them seem to have been followed by tympanites sufficient to embarrass respiration, in one case there occurring an acute cardiac dilatation with myocardial degeneration. The animals give no symptoms of this condition and in the last case cited the beast, while old, ate well and was not distended the evening before death.

When acute gastritis exists (twenty cases) the animal seems uneasy but does not vomit. On one occasion I was called to see a monkey which was retching and seemed in pain. Lime juice was offered and taken, followed by gentian and cardamon, which seemed to give some benefit. 186Somewhat later this was repeated in another case, but observations where this might be useful are rare.

The pathology of gastric conditions offers little to contrast with that of man. The enormous distensibility of the fundal pouch often suggests to the observer the rumen of ungulates. Acute gastritis of one kind or another and acute catarrhal enteritis are the most common lesions noted in the Primates. Involvement of the intestine or colon need not carry with it an increase of signs of illness, although at times one will see an evidently sick animal with diarrhœa. Anatomically the lesions are commonly restricted to the stretches of gut above the ileum, it being rather rare that this division or the colon is affected. Pathologically the lesions are catarrhal with definite involvement of the follicles in about one-third of the cases. In this order toxic and pseudomembranous forms are quite rare and ulcerative lesions uncommon. Colonic disease as a sequel to inflammation higher up is sometimes seen in the follicular varieties, but takes a minor place compared to amœbic dysentery of which we have had several cases; this will be discussed under a separate heading. Degenerative disease of the skeleton is almost always accompanied by a low grade of enteritis but not necessarily gastritis or colitis. The pallor of the mucosa, while at times striking, may be relieved by follicular spots and petechia or pigmentation. Often, however, animals suffering from osteomalacia and rickets come to their end by an acute inflammation of the gut tract.

The bacteriology at our disposal allows no conclusions. Aside from a case probably due to Ps. fluorescens and one with colon bacillus abscesses in the liver, no reliable data are at hand.

Reference to Table 11 reveals the fact that among orders with sufficient autopsies to permit percentages, the alimentary tract in monkeys is in the group of low figures, that the intestinal section is relatively more often 187affected, and that the colon is more often diseased than in other mammalian orders, and is exceeded only by the gallinaceous birds.

The Lemures, of which we have eighty-six autopsies, do not differ much in anatomy from the Primates, however greatly they disagree in habits and outward appearance; their diet is the same. Clinically the slothful behavior of a normal lemur probably obscures symptoms and signs of illness, for our antemortem notes with the exception of a few observations of loose stools, fail to offer a lead as to diagnosis. This order has a large incidence (twenty-three cases) of gastroenteric conditions as shown in Table 11, but some explanation of the figures is deserved. In the first place, only one case of acute gastritis occurred, and this was apparently a part of a general infection, and if induced at all by food this was only secondary. Indeed as one reviews the records it does not seem that the lemurs are easily disturbed in their gastric digestion. Acute and subacute inflammations from bacterial action seem definitely more prominent since they take the catarrhal, follicular and deep submucous form and are frequently associated with generalized infectious processes. One amœbic case was observed and there was another in which a heavy cestode and nematode infestation seemed to have paved the way for bacteria.

The food of this order is received into the fundal part of the stomach, the distensible but normally capacious left and superior two-thirds of the organ. The general shape of the viscus, that of a gourd, permits a fairly sharp separation of the fundal and pyloric sections, so definite indeed that the pathology of the two parts was studied. The intestines vary in length, but in the land carnivores are relatively short, narrow in lumen and rich in wall. A cecum, or at least a blind end of the 188large gut made by the insertion of the small intestine above the tip of the colon, is suggested in all families, although, as in the bears, it may be quite insignificant or rudimentary. Theoretically no stasis should occur at this point. The colon is short in all carnivores and, like the small gut, with a heavy wall. The comparative simplicity of the carnivorous gut tract, the ability of many of these animals to disgorge, the suggestion of high resistance of the upper end of the tract to infection and the ease with which diarrhœa can clear out the tube, would seem to warrant the expectation that inflammation would not be serious. Such, however, is not the fact for, on the contrary, they have shown a higher incidence than any other order for which we have adequate comparison. Anatomically considered their stomach occupies the second place in vulnerability, next to the marsupials, and their intestines the highest place; this indicates of course that combined gastric and intestinal disease has often occurred. Involvement of the colon occupies the second place, in ordinate susceptibility, being exceeded only by the monkeys, due to heavy parasitic infestation, but would occupy the first place were the eleven amœbic dysenteries in monkeys subtracted from their total, a subtraction which might be allowed since it represented an epizoötic outbreak.

Etiologically considered, it would seem as if the influence of incorrect feeding were of little importance, and from one standpoint this is probably the case. Acute fermentative or irritative processes are not common at all, while more inflammatory pictures, catarrhal, erosive or ulcerative, are the rule. There is another phase to the term incorrect food, that is incorrect in its cleanness. During 1912–15 there was an increasing mortality among the cats and dogs fed upon horse meat, mutton and fowl heads. Early in 1916 the butcher shop was reconstructed and thoroughly cleaned and covered galvanized pans supplied in which to transport the food; these pans were 189scrubbed and scalded after use. Since that time, infections inflammations of the stomach and intestines have shown an ever increasing downward incidence, which result, there having been no material changes in other directions, I do not hesitate to ascribe to the improvement of butchering and dispensing engineered by Dr. W. B. Cadwalader.

Helminths seem to be of importance in this order both by reason of the percentage of autopsies in which they presented the most probable or at least most suggestive cause and because uncinaria and strongylus have been seen attached to the wall and a large bulk of known irritative cestodes have occupied the lumen. Physical objects, stones, bones, wire, may cause irritation enough to activate bacterial action or may actually penetrate the wall; the latter action is well known. In so far as practical application of this is concerned, it teaches to feed whole, unsplintered or ground bone.

The distribution and character of pathological lesions according to the region of the stomach is what might be expected from the shape and physiology of its parts. True inflammatory processes are best, and in some cases only seen in the pyloric half of the viscus, while the changes in those few cases believed to be fermentative or irritative in nature were largely confined to the fundus. Dilatation of the latter part may be understood because there the muscular coats are about equal to the mucous in thickness and one-half the width of those at the pylorus, but why inflammatory processes should not be so developed in the fundus is not clear unless the greater availability of mucus protects the secreting wall. Not only does acute inflammation reach its most definite form in the second part of the stomach, but the irregular pigmentation, mammillated overgrowth and atrophy or ulceration of chronic disease are likewise best seen in this part.

190Acute enteritis, of all varieties, is seen more beautifully in carnivores than in any other order of mammals, and nowhere can it be studied better. Its gross appearance is that of the text-book and its minute character even more instructive. I have used a slide of acute catarrhal enteritis in a lion for the illustration of this lesion for the Text-book of Pathology by Doctor Stengel and myself. However, as is known to all who have paid any attention to enteritis, the postmortem findings are usually much less definite than clinical observations would warrant one to expect. The Carnivora not uncommonly show intestinal congestion, mucous membrane swelling without edema or opacity, congestion of the spleen, cloudy swelling of the liver and kidneys and perhaps mesenteric lymph node edema. This picture we have viewed as a toxic affair of some sort or a bacterial infection not yet far enough advanced to produce catarrhal or ulcerative enteritis and septicemia. In such cases the carnivorous intestinal mucosa offers instruction. The epithelium is vacuolated or fringed on the free edge or may be missing altogether. In the depths mucus formation is very active, and where it is going on, round cells seem attracted, collecting in groups in the villus or in the subjacent submucosa. Perivascular round cell increase may be noted. Plasma cells and granular eosinophiles are common, but I cannot state how important the latter are in the general picture because of the frequency of parasites in carnivores. The central vessel of the villus and the arterioles of the submucosa are injected. Lymph follicles may or may not be enlarged, but if so usually fail to show a germ centre.

Colitis alone is not common in this order, but as an extension process or involvement at the same time as the upper levels it occurs occasionally. The only fact I wish to record and one which I would emphasize because of having seen it recently in a human case of chronic colitis, and since it does not appear important to systematic writers, is superficial blood supply. The capillary network 191of the colonic villi, while rich, is in the form of a fine plexus just under the epithelium. In the cases studied these vessels become quite distinct and possess much more definite walls, often bordered by mononuclears, while connective tissue is more evident at the bases of the villi and deeper. This may help in deciding the existence of a colitis.

Bacteriologically the most instructive experience to report is the discovery that a small outbreak of enteritis among small Carnivora, chiefly cats, fed upon fowl heads was due to Bact. paracoli, or at least this organism was found in the intestinal mucosa, spleen, and heart’s blood of three cases. The type of enteritis was hemorrhagic and follicular. There was also a case of septicemia apparently emanating from enteritis due to Bact. suipestifer in a lion (Felis leo). These facts bring strongly to attention the modern teaching that meat poisonings of the Gärtner type are to be considered as infectious and not of the so-called ptomaine group.

Pinnipedia, while related closely to the Carnivora, are grouped in a suborder in our classification and because of their restricted diet are treated here in a separate paragraph. The tract is peculiar in the strong tubular stomach sharply bent upon itself, the great length of the small gut (upwards of a hundred feet in some genera), and the practical absence of a cecum. Pathologically speaking, the most striking lesion of these animals is ulcerative gastritis, a process usually most marked along the posterior-superior surface, but not confined thereto. Upon inspection the gastric mucosa, normally supplied with low regular rugæ, is much distorted by swellings upon the top of which are irregular ragged ulcers with rounded elevated but not frayed margins. The density of the edges indicates much infiltration of the deep mucosa and submucosa; this can be confirmed by microscopical examination. One attempt to study this gastritis bacteriologically was fruitless. Sections of one case 192showed streptothrix-like masses while in another case bacterial colonies and yeast-like bodies were found in adjacent lymph nodes. The genesis of this condition might lie in injury by fish fins or by foreign bodies, of which large numbers are found at times (a pint and a half of stones, marbles, and sticks were found in one stomach). Gastritis has been the starting point of septicemia on two occasions, and three times an acute exacerbation or new implantation of infection occurred, with extension into the intestine. It is interesting that all the deaths of Pinnipedia with gastroenteric conditions occurred in the winter months.

Insectivora are represented by two common European Hedgehogs. In one there were three shallow but shelving ulcers in the stomach which had bled sufficiently to weaken the animal; free blood was found in the intestine. The other specimen was diagnosed at postmortem as having catarrhal enteritis involving nearly the whole small gut, but histological section did not confirm this.

As one descends the zoological scale the first gastrointestinal tract prepared for the nutritional care of bulky food is to be found in the Rodentia. This order presents a great variety of shapes and arrangements of the stomach, but the outstanding feature, with very few exceptions (cf. spermophiles), is the development of the cardiac and fundal divisions ostensibly for the reception of a large bulk of coarse food to be digested at leisure. Some genera like the hamster (Cricetus) have a stomach closely resembling the ruminants, while that of the spermophile suggests the equine stomach. The pyloric end, variable in many ways, greatly resembles the abomasum. So too the duodenum is large, loose and distensible while the copious small gut ends in a very large cecum, shaped at times in a manner which has led to the term “colonic stomach.” The colon is variable and not always supplied with longitudinal bands and sacculations.

193In regard to incidence of gastrointestinal disease, rodents occupy a middle position in the table. The stomach seems a vulnerable section of the tract. Dilatation of the left hand section is common, due, to all appearances, to fermentative processes which have as a result the softening of the mucosa so that even immediately after death it will separate almost entirely. In these cases the pyloric part need not participate but may remain flat, smooth, soft and pink. This condition is slightly more common in the compound than in the simple stomachs. In some of this order, especially rats and cavies, there is a fermentative gastroenteritis expressed by injection and edema of the pylorus and duodenum, and much frothy mucus. It was at first thought that some relation might exist between this condition and the absence of the gall-bladder, but it occurs in varieties possessing this structure. The reaction of the intestine to irritation in this order is peculiar in two ways, the occurrence of mucus and the activity of the lymphatics. In all the inflammations from and including the stomach to the cecum, mucus is conspicuous. At times it is thin or loose and mixed with contents, while at others it forms a relatively close covering for the mucosa almost like a false membrane. Rodentia are peculiar in the promptness and clearness with which the follicles of the intestinal wall and mesentery enlarge in inflammation. They appear as pale, well outlined or diffuse opacities in the wall or as distinct plaques prominent on the surface.

The Proboscidea are represented by one Elephant (Elephas indicus), in which a mild catarrhal change was seen in the middle stretches of the small intestine. This was of little importance as a cause of death, there being several other diagnoses, and was probably a terminal affair.

Hyraces, of which we have a total of seven examples, present two mild involvements of the intestine but none of the stomach. It would appear from the records 194that the intestinal condition had little to do with the death of the animals, and unfortunately no microscopic slides were made. Because of the curious formation of the large gut, notes of both ceca were made in one case, and can be condensed as follows: “The upper or anterior cecum presented a shaggy pearl gray mucous covering, closely attached to the mucosa. This cavity and the posterior ceca were packed with dry crumbling feces. Small thin-walled cysts were seen in the tips of the lower ceca. Duodenum was congested and mucosa swollen. Stomach contained dry, poorly digested food. No parasites were found.”

The Edentata are represented by an Armadillo (Tatu novemcinctus) and an Anteater (Myrmecophaga tridactyla.) The former had a prolapse of the rectum accompanied by colitis but it is impossible to decide the priority of the two conditions since the former is known to have existed long enough to have permitted the latter to develop. The Anteater had a distinct mucocatarrhal enteritis in which bacteria played a part since involvement of the liver, spleen, kidney and lymph nodes also existed. The beast was in good condition upon arrival, but did not become accustomed to the proffered diet, and was distinctly anemic at death.

The Ungulata, so-called for their hoofed and horned character, are also associated anatomically by the construction of their gastrointestinal tract. However, the order of the list as given on page 44 does not represent their historical development nor does it accord with anatomical arrangement of the tube under discussion. The last three families of Artiodactyla are perhaps the simplest in the construction of this tube, or at least take an equal place with the Perissodactyla, while the remaining families of the former suborder have a complex tract of generally similar architecture. This whole order has, however, an alimentary tract anatomically suited for the consumption of bulky vegetable stuffs and shows an 195attempt at adjustment between the food, the methods of mastication, the area of digestive surface, and the bulk necessary for nutrition. The number of factors opened up by the many variations between this complex tract and that of the carnivorous simple tract is so great that I shall attempt only to contrast the anatomy and pathology of the simpler ungulate tracts and the complex ruminant apparatus.

The simpler gastrointestinal tract is possessed by the Perissodactyla, and by the following families of Artiodactyla, the Phachocœridæ, Suidæ and Tayassuidæ. This consists of a stomach with a single cavity (some Peccaries have partitions but no true septa with strict histological differences) divided into esophageal, cardiac, fundal and pyloric areas, dependent upon the nature of the lining epithelia and the absence or presence of glands, as well as the nature of the tubules. The duodenal section is ample and may be sacculated while the intestines are small in calibre and rather sturdy in wall. The cecum is relatively very large, well supplied by longitudinal bands and sacculations; the colon is relatively short but quite capacious and sacculated.

The ruminants and other remaining members of the Artiodactyla have a compound stomach suited to the separation of coarse and fluid foods and the retention of water, and so arranged that boluses of different densities are distributed as needed. These divisions are histologically as well as grossly different. The first three, comparable to the esophageal section of the simpler stomach, are reservoirs or channels, while the fourth or true digestive section, is divided into areas corresponding to fundus and pylorus, possessing the appropriate type of gland. The duodenum in this group is narrow, as is the rest of the small gut, and has delicate walls. The cecum proper is short and of variable width, but never as great as in the group first discussed, while the colon, an intricately wound tube, is narrow and very long. Certain 196of the first group (Peccaries) have a colon of this type, but it is not so complicated as in true ruminants.

These complications seem designed to permit of a long retention of coarse food of low nutritive value per bulk for a time sufficient for full digestion; reverse adaptation of large size of stomach and colon may be explained on the same basis. Let us now examine these two groups to discover their pathological reactions and the nature of the lesions.

Ungulates as a class stand in a position equivalent to the Primates in the incidence of gastrointestinal diseases. They show a conspicuous percentage of cases apparently due to incorrect food and, coupled with this, a high percentage of gastric involvement, being exceeded in this respect by the marsupials only (there is an adequate reason for this—see below). Cases ascribed to bacterial or parasitic agents are not numerous. Analysis of the records of the two groups discussed above brings out some interesting facts. Consultation of Table 12 shows percentage comparisons, based on the number of autopsies, of lesions in the various sections of the tract. Group A, that with the simple stomach and the short capacious colon, is represented by forty-four specimens, while Group B embraces 321 animals. Perhaps the use of these two widely differing figures for comparison is open 197to some objection which might be final and decisive were not the figures so definite. At a glance one can see that Group A has involvement more marked high in the tract while Group B has more disease in the intestine and colon. Certainly gastritis is more common (five times) in the A than in the B group, while enteritis is more common in B (over three times). No case of chronic enteritis or of involvement of the colon is recorded in animals with a simple stomach and a wide hind-gut. This may be read either in terms of vulnerability of the stomach or in the degree of resistance of the respective groups.

Consideration of the local factors of the stomach brings to light at once the fact that incorrect food entering the simple stomach could attack the softer, less resistant glandular section of the fundal and pyloric areas whereas the rumen and psalter of the compound organ, with their stratified epithelium devoid of glands, act as barriers or as places where detoxication of irritants might take place. In both groups bulky food is packed to the left, the esophageal and cardiac section in the simple form, the rumen in the compound. Soft or liquid food may pass into the psalter and abomasum of the ruminant stomach almost directly since it has not the force or bulk to push aside the valve-like fold of wall at the junction of esophagus, rumen and reticulum. For this reason, if for no other, the character of soft food supplied to this order must be unexceptionable.

It has not been possible to follow out the layering of diets as Scheunert did when showing the course of various foods before they are mixed at the beginning of the pyloric compartments. We have seen two cases in ruminants which seem to indicate that soft food had passed into the right side cavities of the stomach, there to cause irritation, while the rumen remained quite normal. It seems, however, accepted by veterinarians that excessive soft food may be followed by trouble in the digestive stomachs, while excessive dry food may cause distention 198of the left hand sections. So far as I know, the relative incidence of gastric disorders in the above outlined groups has not been pointed out before.

The pathological types of gastroenteritis do not present many unusual features. Simple injection of vessels during digestion seems more evident in this than any other order, while mucus production seems less marked. The mucosa of the reservoir portions may, in simple overfilling and fermentative distention (gastric tympanites), be quite normal or dull red; when active fermentation has occurred it may be digested and peel off. More or less true inflammation as seen in the digestive stomachs is definitely better expressed in the compound ruminant organ than in the simple equine variety where congestion and edematous swelling with hemorrhage form the usual picture. True catarrhal changes both gross and minute, are often well seen and ulcerative lesions are not uncommon; ulcers are unusual in the simple stomach. These statements hold good also for the small intestine. Enteritis affects the duodenum and jejunum more in the Perissodactyla and swine than in the ruminants. Ungulata do not react with hyperplasia of the mural lymphatics as do many other orders, but the swelling of the mesenteric nodes is often noteworthy. As might be expected this is more definite with catarrhal changes and therefore best seen in the ruminants. In the colon, however, the solitary follicles are often quite prominent in simple inflammation. Histologically the greatest changes seen in this order are superficial degenerations with mononuclear increase in the deep submucosa, mostly arranged in perivascular fashion. The villi do not contain the large number of cells seen in the Carnivora.

Consultation of the figures for this order in Table 11 arrests attention at once because of the peculiar percentages found under the detailed factors. 199Thus food is of no moment as a disturber of the alimentary tract, while bacteria and parasites are high in importance. The gastric segment is more often attacked than any other portion and slightly more often than in the nearest order, Carnivora. These unusual figures deserve explanation, to which purpose it will be necessary to consider the anatomy of the organ and to discuss why bacteria and parasites stand so high in etiology.

Marsupials are divided into six families in our classification (see page 44) which in regard to their diet, range from largely carnivorous (the first two) through those choosing mixed insects, fruits and vegetables (the second two) to those eating vegetables and grain (the last two). The stomach of these animals does not vary exactly according to their diet, the first four, opossums, dasyures, bandicoots and wombats, possessing an organ closely similar in outline and construction and resembling the carnivorous variety, while the phalangers and kangaroos have a stomach entirely different from the first four although somewhat similar to one another. The first group has a round or irregularly elliptical organ with the esophagus and pylorus close together along the lesser curvature. The wombats have a bank of glands surrounded by a capsule, near the cardia. The stomach of the first four animals is divided into cardiac, fundal and pyloric parts by the construction of their mucosa, the first mentioned division being a high, rounded pouch, rumen-like, well to the left. The phalanger’s stomach is more elongated, the two openings well separated and a fissure is found in the right end of the lesser curvature which serves to separate the pyloric part from the rest. The Macropodidæ all have a stomach resembling the human colon in being elongated, with longitudinal bands gathering it into sacculations. There is a distinct esophageal section to the left with a blind sac suggesting an ungulate rumen, a long tubular fundal, and a sacculate pyloric division.

200The small intestine of the order starts with the opossums as a stout muscular and mucous tube fitted for meat eating, but as one proceeds to study the families downward in the list this tube becomes more delicate and longer. In the first two families the cecum is rudimentary and the colon very short as in cats, but the length and capacity of these parts increase through the bandicoots and wombats until in the strict fruit, vegetable and grain eaters, phalangers and kangaroos, the cecum is long and capacious and the colon relatively long and roomy.

Table 13 contains an analysis of the forms of gastroenteritis as they were described in the two groups of tracts, that resembling the carnivorous, that similar to the herbivorous intestinal construction, and according to the factor believed to be responsible. In the first group gastritis of an acute nature occurred in 9.6 per cent. of the 103 specimens. They were chiefly catarrhal in character and seem for the most part secondary to verminous infestation; at least six of the ten cases were associated with parasites. The process microscopically is catarrhal and deeply infiltrative. Group B has a high incidence of gastritis and here the evidence of bacteria or toxins is quite plain. Several of the cases were in animals showing also Kangaroo disease of the jaw with pneumonia or septicemia; the gastric lesion of streptothricosis will be described under that heading. The character of gastritis 201without jaw disease is somewhat different from that with it. Pathologically the process is a congestive and superficially necrotizing affair, forming upon the tips of the folds, small gray erosions or flat shallow irregular ulcers, which upon histological study consist of loss of tissue of the mucosa and some deep congestion with round cell groups but no reaction deep in mucosa or submucosa. True catarrhal inflammation has occurred, but not like in the opossums.

Chronic gastritis in the simple stomachs is almost exclusively in opossums harboring Physaloptera turgida, a worm which fastens itself more or less firmly in the mucosa and probably, with the assistance of bacteria, causes sufficient irritation to produce a hypertrophic change in the deeper layers and a destruction of the glands where it holds and a distortion of those nearby. One is reminded that Fibiger found spiroptera to be responsible for adenocarcinoma in rats; no tumor formation has been found in these animals, although one opossum with such a stomach had an adenocarcinoma mammæ. Small hemorrhagic spots may occur in the deeper layers, possibly where the worms have bitten. The rugæ are irregular or interrupted by knobs and papillæ.

Group B, stomachs showing chronic change, were all kangaroos. The three cases resembled the infiltrating necrotizing lesions as discussed under ulcers (page 175). The process showed an infiltration of the subsurface tissues with a gray slough over the densest part. The mucosa as a whole was irregularly rugous and spotted with red gray areas.

Altogether one gets the impression that in the simpler stomach, reactive inflammation is most prominent, while in the colonoid stomach degeneration is greater than reaction.

Intestinal lesions in marsupials are not common and not peculiar except in that they carry out the pathological 202reaction as seen in the stomach. The carnivorous intestine shows frank catarrhal changes, the herbivorous presents congestions and superficial necroses. These two groups then follow the descriptions as already given for carnivores and ruminants.

The colon presented in the first group, simple catarrhal or follicular change. In the second division the lesions resembled those in the stomach; they were only once of the three instances associated with streptothricosis.

The class Aves has been treated in the chart precisely as have the mammals, but it is not possible to make the accurate diagnoses or to separate groups of lesions according to anatomy as was done for the latter class. Upon the average there is more gastroenteritis among birds than mammals, but when looking for an explanation of this, it was unfortunately necessary to enter in the “undecided” column of Table 11 a very great number of cases. This column would be greater relatively were it not for the parasites in parrots and gallinaceous birds, the entries for which are high. Besides this fact and that the owl stands at the top, the pigeons at the bottom of the list numerically, no further general statements are allowable. There are several orders with high values among those of which insufficient autopsies are at hand to cast percentages.

The avian alimentary tract seems to have developed according to the character of food the different varieties of birds consume if one may judge by the construction of the bill, the gastric musculature and the intestinal wall. Zoological classification has only secondarily considered this point, it being made incidental to the habits and habitats of birds. For this reason the orders as outlined on pages 44–46, placed as they are in historical evolutionary position, represent with few exceptions groups which have differing diets and, by the same token, differing gastrointestinal 203tracts. Classifications based upon habits of life (Raptores, Cantores, Natores), prove likewise too broad or too heterogeneous, while systems making character of food the chief criterion though apparently correct in reasoning and helpful in certain orders, (Accipitres, Galli) are found to present copious exceptions; moreover we are imperfectly informed of the exact diet that many families require or resort to in absence of their preferred food. I shall therefore discuss the chief diseases and distributions according to our classification, preceding the discussion by a brief résumé of the anatomical peculiarities of the avian alimentary tube.

The first digestive burden falls upon the proventricle where the principal juices are secreted while the muscular stomach or gizzard assumes the duty of gastric mastication. The lateral muscular bellies of its heavy wall grind the food and mix well the gastric juices. Its mucosa probably supplies only lubricant. In birds whose food is hard, corn and the like, this grinder is supplied with a dry horny internal layer, while a thick, moist, soft, epithelial surface is sufficient for carnivorous birds. All kinds of gradations exist between these extremes. The mucosa of the proventricle is always soft, but quite deep to permit the placement of compound tubular glands.

The relation of size of these two parts is subject to many variations.^[22] The proventricle is larger proportionately in meat eating, fish-eating and fruit eating birds, the gizzard having the greater size in granivora and insectivora. In certain birds the mucosa of the two is separated by a very soft thin zone, an important fact in Psittaci since at this place spiroptera seem to penetrate to the glandular layer of both organs.

The duodenum begins in practically all birds, from a spherical cavity at the pyloric end of the gizzard, to be accredited anatomically to both sections. It passes downward, 204forms a long loop enclosing the pancreas, its distal end lying under the liver and near the gall-bladder. Near its end it receives the major bile and pancreatic ducts; smaller ducts from the liver and pancreas may enter near the pylorus or elsewhere along the loop. The small intestine is usually simple in its coils, but in the birds that eat grain, grass and greens, may be long and complicated. So too the colon, usually a very short segment, may be increased in the just mentioned group while the ceca are only of any considerable length in herbivorous birds. The length of the ceca is, according to Owen, related to the availability of food and the need the bird may have for exhausting the nutritive value of it. In carnivorous birds as in similar mammals, the whole gut, but especially the hind-gut, is very short and the ceca small or absent. But so they are in picarian birds which are chiefly herbivorous, but may eat meat.

The double-muscle stomach, that with the two lateral plates and tough epidermal internal coating, is seldom the seat of disease. An excess of greens in the diet sometimes seems to soften or macerate the lining, while an excess of pebbles may cause erosions. Upon severe irritation this internal layer assumes the appearance of tanned leather and may crack. The proventricle of such a gizzard seems rather resistant to disease, particularly one would say, to infective processes, for catarrhal or ulcerative inflammation is uncommon. The saccular stomach with uniform muscular walls continuous with those of the proventricle, such as is seen in raptatory birds and parrots, offers a somewhat different picture. The internal membranes of these organs are definitely softer, seeming to swell with great ease, and the glands themselves are smaller both at the fundus and outlet, a construction which may favor their closure by swelling from simple congestion and edema. Catarrhal and ulcerative 205processes are definitely more common in such organs than in the first type or true gizzard.

Enteritis of all orders is most outspoken in the duodenal loop, but a determination of the lesion must be made with some care. All the signs of intestinal inflammation—congestion, swelling and opacity, excess mucus or mucopurulent covering—must be present to justify a gross diagnosis of enteritis and even when these exist one fails at times to confirm the finding by microscopical section. These changes may be simulated by digestive activity so that it is but reasonable to demand them all in a clear cut fashion before applying the term enteritis. However, it is well known that cases in both human and veterinary medicine giving a satisfactory clinical picture of this disease may fail to show to the naked eye and under magnification the changes expected.

In the human being, the carnivore and the ruminant, the ileum presents the most definite picture of enteritis. In the bird, the duodenum shows the prominent lesions, and with the exception of specific diseases like blackhead, is always involved when the smaller coil of small intestine is affected. This is true whether the enteritis be nonspecific or be associated with cholera of chickens, ducks or parrots.

The colon presents peculiar lesions in but few birds. Ulcerative and necrotizing processes have been encountered in three orders, Psittaci, Anseres and Herodiones, suggestively like the specific forms seen in the ceca. Microscopy and one unsuccessful culture failed to reveal a mould or protozoön. The condition appears as a gray white plaque in the cloacal wall or it may spread up to the colon and around the urethral orifices. At times it is superficial upon the mucosa and may be covered by a pseudomembrane.

206The chief interest in the ceca centres about enterohepatitis either of heterakis and amœbic origin or that supposed to be due to coccidia or Bac. scoticus. This specific form has been encountered only in Galli (three of the four families). It has been so well described by Hadley, Smith, Morse and Cushman that it is unnecessary to discuss it since we have nothing to add to its pathogenesis or pathology. At a later time some attention will be given to our experience with Quail disease. What is more interesting from a comparative standpoint, besides having a bearing upon blackhead, is the discovery of heterakis in the ceca, and hemorrhage and fatty change in the liver without amœbæ or coccidia in either place (unfortunately no bacteriology was done), in a Sebastopol Goose (Anser domesticus), a bird which has ceca not unlike the gallinaceous varieties. This is a single observation and must be treated expectantly.

Microscopically the avian digestive tract in its various inflammatory states presents a few noteworthy features. The primary reaction, sometimes the only one, to irritation is injection of the vessels in the villi or deeper mucosa. To this, however, is nearly always added a granularity of the epithelium, without much evident mucus (goblet cell) formation. When the epithelial degeneration is marked there appears a round cell increase in the deep mucosa shortly followed by a similar infiltration into the villi. True catarrhal enteritis as described for the cats is not as common as some combination of the changes just detailed, but when it occurs is best developed in the carnivorous avian tract. The most striking cellular finding is the round cell of the infiltrate. It is of the middle lymphoid size with clear protoplasm, or, when late in the disease, may be small and so-called adult. Polynuclears, unless eosinophilic, and endothelioid cells are rare.

The foregoing are general remarks concerning the pathology of the avian tract, and we are now ready to 207discuss briefly the reactions of the orders. I shall, however, omit mention of those in the right half of Table 11.

Passerine birds are represented better than any other order because they are more numerous in nature and therefore exhibited more generously in collections. This order is not especially vulnerable as to its alimentary tract, but this tube is often affected by tiny stones, bits of rust from cages and by acute general nonspecific infections to which these birds are quite susceptible. Upon many occasions intense congestion with and without tiny hemorrhages in the duodenum are all that can be found in the little birds and the diagnosis of enteritis is put down. Only about one-tenth of these birds have shown more or less definite catarrhal changes. Many birds have heavy infestation with worms which may activate bacteria.

The Striges and the Accipitres will be discussed together because of the similarity of their tracts and their diets. The reaction of their gastric complex has already been mentioned and what was written there can be extended to the intestine. The type of lesion is catarrhal and seems to be “meat bred” although this cannot be proven. They never have given positive heart’s blood cultures so that the disease seemed not to be septicemic. Liver and spleen have harbored colon and paracolon bacilli. It will be noticed that they have the highest incidence of gastric disease.

Psittaci, birds with a tract similar to the last two but with a captive diet of seeds, fruit and vegetables although they may eat small animals and insects in the wild, present figures under bacteria and parasites which explain the involvement of the alimentary organs. We have had two acute outbreaks of what seemed to be fowl cholera, judging by the pathology and the isolation of Bact. gallinarum and we have frequent deaths with the same gross anatomy from which bacterial isolation has not been tried or was unsuccessful. At all events the enteritis of parrots is often a definitely infectious affair. 208We have also isolated Bact. psittacosis on two occasions. Separation of the birds and cleansing of the exhibition spaces seemed to stop the disease. The lesions are hemorrhagic and superficially necrotizing in this group whether or not they are septicemic. Some have also shown a follicular appearance both grossly and minutely, one of which cases was associated with Bact. psittacosis.

The effect of animal parasites is chiefly exerted, for this group, in the proventricle where the Spiroptera incerta occupies the lumen and penetrates the mucosa or burrows under the inner lining of the gizzard. Enteritis is not especially associated with this infestation, death resulting more from inanition than infection; some few cases have had enteritis, others pulmonary disease.

Columbæ are not susceptible to disease in the parts under consideration. This order seems to have some tissue resistance, for their lesions are quite frankly catarrhal, more so than in most grain-eating birds.

The figures set against the Galli are swollen by the number of cases of enterohepatitis of one sort or another. Extracting these from the total leaves the order among the lowest. Their lesions are congestive and hemorrhagic, although they may show catarrhal cases. They seem to be able to summon mucus more readily than many other birds.

Anserine birds, though not very high in figures, present three conditions worthy of note. In the first place, acute simple gastritis occurs often, sometimes associated with foul green food, sometimes without any apparent cause. From the number of times that foreign bodies are present it seems probable that they contribute in some way. Excessive stones and sand, bits of glass, collar buttons and the like are sometimes found. Then the form of acute enteritis has always a hemorrhagic tendency, at least in the submucosa, while the mucosa may be swollen, opaque and covered with mucus. Upon histological study these intestines show intense swelling by cellular infiltrate 209and disappearance of the tips of the villi. The third observation concerns what is apparently a subacute or chronic process although this is not supported by microscopy. Certain birds will have a cast of mucus and epithelial detritus rather closely adherent to the wall. Under the microscope there may be slight evidence of chronic inflammation or there may be little amiss. These birds have usually been large ones, and several have come from the separate goose pens, not from the open lake where many birds are kept.

The struthious birds deserve a word. They have had a great deal of enteritis and mostly of infectious nature. Two instances have arisen from bird diphtheria, one from cholera and six from what later seemed to have been anthrax but was not diagnosed at the time. The character of the lesions in the struthious intestine tends to be hypertrophic and superficially erosive if not ulcerative. The changes are found with greatest clearness in the lower duodenum and small coil.

Having discussed the inflammatory conditions of the gastrointestinal tract we now come to the more or less definitely mechanical abnormalities, whether or not they depend upon preëxisting inflammation, and the subject of constipation will claim first attention. In the human being this condition is the result of bad habits more than any other one thing or all things together, I think it will be admitted. In the lower animals perhaps no such thing as habit of defecation exists so that one can with more certainty hold incorrect food, chronic catarrhs or physical obstruction as responsible. Veterinarians look upon excess of dry food and irregularity of work and food periods as the principal causes of constipation. These factors do not hold in zoological collections. As a matter of fact constipation is of minor importance in this menagerie, but a certain few cases are worthy of note. It 210has been mentioned in the diagnoses in only a little over 1 per cent. of the total, and of these the records indicate its importance only ten times (.2 per cent.); a few notes of these cases are appended. The first place of incidence is taken by marsupials (six kangaroos and one opossum), the second by ungulates (largely ruminants) and the third by Primates. It will be noted that with exception of the opossum, herbivorous mammals occupy the first places of incidence, carnivores falling well behind the orders named. This condition is quite infrequent in birds and is usually associated with the presence of seeds or parasites or with impaction in the ceca.

Primates, almost exclusively feeders upon carbohydrate and soft protein food, have shown as causes of constipation two outstanding conditions. A low grade of colonic catarrh with excessive pouchings of this tube has had constipation associated with it three times. One of these cases had small coproliths in the diverticula, one other a fecal concrement in the cecum. Another group of these cases with evidence of delayed passage of feces shows chronic peritonitis with adhesions, one of which seems certainly due to filaria in the peritoneal sac.

The seat of constipation in monkeys is practically always the colon. The carnivores while occasionally showing hard fecal masses packed into the colon, more often exhibit a constipation in the ileum. One case presented a nearly empty colon with a long scybalum just above the cecal valve. There is no peculiar associated pathology in the notes at my command.

Ungulata, showing next to the highest incidence, has its stoppage chiefly in the colon, but the lowest stretch of the ileum may contain balls of feces. In nearly every case one finds some grade of colonic catarrh. In two instances, there being a proctitis, it seemed as if the animal voluntarily restrained from defecating because of pain. The caput coli is the seat of stoppage in the Rodentia.

211Marsupials give such a high relative incidence that especial search of their records was made, without, however, very definite result. In three of the seven cases an acute general infection existed, in one an acute peritonitis which seemed to emanate from a small ulcer in the ileum, in one an injury to the anal region was found while in the remaining two the notes would suggest that the lower intestine was atonic, judging by its distention, translucency and pallor. In five the stoppage took place in the large bowel alone, in the others both divisions being affected.

It is often difficult to establish a diagnosis of constipation in birds because many varieties form a long rather dry mass in the lower small intestine, to be moistened in the cloaca for discharge. Still again the groups with capacious ceca are apt to have them filled normally with firm casts. Diagnoses of fecal inspissation and stoppage in the smaller tube have been made seldom, but one must consider also the obstruction offered by excessive urate collections either in the cloaca or lower ileum which will amount to a constipation if the cloaca be over-dilated and dried urates mixed with dirt or feathers cover the anal opening.

The causes of this condition in birds are usually mechanical, inflammation being found in a small minority of cases. In the small passerine birds, seeds, sand, or parasites form the commonest findings. This is also true of parrots, while excessive urate collections are noted for both these groups. The gallinaceous birds present two reasons for fecal stoppage—disease of the ceca (see pages 205–6) and cloacitis probably secondary to anal closure by excessive urate collection. Uratic stones, varying from one to five millimetres in diameter, have been found in the cloaca in several orders. In only one case, a pheasant, did they cause ulceration and cloacitis. Sand, rust, grains and the like are found frequently, and sometimes in groups of birds, indicating that the specimens 212had not been put upon the correct flooring or caging. Unbroken seeds may obstruct the lumen.

Although the following is not constipation it is well to cite at this place an experience which amounted to mechanical intestinal obstruction. A number of finches were subjected to postmortem and found to have whole white millet seeds in their intestines, this being the only discoverable cause of death. Investigation revealed that during the night mice ate the canary seed in the pans, leaving only the millet, which the hungry birds consumed whole. Small birds can take a few millet and crack them when eating leisurely, but apparently not when hungry. When the food was removed at night the trouble ceased.

Obstruction by sand is well illustrated by a peculiar form of pica, in a goose, which is worth citing, and calls to mind the sand disease of horses:

Canada Goose ♂ (Branta canadensis canadensis).

Diagnosis.—Masses of sand in entire intestinal tract. The general condition externally and internally is good. The crop is distended like a sausage, quite firm and the overfilling is obviously due to sand in which very few stones, which could be called pebbles, are found. This mass continues into the esophagus making the whole tract impassable for food. The mucosa is a little pink and dirt-stained in places but is not visibly inflamed. The gizzard is contracted over a mass of sand but no food. Sand in more or less definitely packed condition is found all along the gut tract, in one place in the small coil it being quite as tight as in the crop and no lumen remaining. Sand and bits of shale are found in ceca. The organs are apparently healthy, slightly pale perhaps, but certainly not distinctly anemic. No infection exists. The aorta, just above renals, has a 15 mm. × 2 mm. pale opacity of same consistency as the rest of the vessel, just perceptibly higher than surrounding surface.

“Sand disease” has occurred in a Persian Wild Ass (Equus onager) causing in this case ulceration, perforation and peritonitis, a Common deer (Mazama virginiana) and a Chapman’s zebra (Equus burchelli chapmani). The collection of sand is always greatest in the caput coli, but may coat the large bowel to the anus.

213Larger and more definitely obstructive physical objects are found in both mammals and birds. We have on record a lion (Felis leo) and a tiger (Felis tigris), which swallowed pieces of bone large enough to be stuck in the small intestine and completely occlude it. Smaller objects like buttons have been found even in the passerine tract. Worm masses may occupy such a large part of the lumen of the tube as to constitute a physical obstruction. This is definitely less important in mammals than in birds, especially in the passerine order of the latter class.

Dilatation of the intestine aside from that occurring in connection with fermentation, constipation or ileus, in other words chronic atonic dilatation, has not been encountered. Acute dilatation has been found in several orders under the picture known for domesticated animals. Its pathology and incidence have already been discussed.

Ileus or acute intestinal obstruction may be divided for our purposes into intussusception, volvulus, strangulation and paralysis from interruption of mesenteric circulation. Examples of all these varieties have been encountered and illustrative cases will be cited. In so far as incidence is concerned, the Ungulata and Carnivora greatly outnumber all other orders, showing seven cases each; the sum total in all other orders is but eight. Upon re-reading some of the protocols I have, however, excluded three invaginations in the carnivores, one each in the ungulates and rodents, as probably being postmortem or shortly antemortem occurrences; two had very early peritonitis but other things, sufficient to account for death, were present. These deductions bring the total cases of ileus in mammals to seventeen. Five cases in birds will be discussed briefly.

Primates present one case of volvulus, one of intussusception and one of internal strangulation. The first displayed the entrance of four inches of ileum into the 214colon with such swelling of the wall as to prevent reduction. The exciting cause seemed to be an enteritis, the cause of death a peritonitis. A white-collared mangabey (Cercocebus collaris) was the victim of volvulus probably favored by an anomalous position of the transverse and descending colon which lay to the right, the latter traversing the abdomen obliquely from right to left to reach the pelvis. The volvulus occurred in the ileum just above the cecum, the twisted part being found adherent by the peritonitis. The third case is a strangulation due to peritonitis from filaria and adhesions between stomach and colon from a colitis and pericolitis due to cestodes, one of which was found deeply implanted in the colonic wall.

Two cases of intussusception are noted (after deductions above) for the Carnivora. They both occurred in the ileum, one restricted thereto, the other extending into the colon. In both a vague history of being “off their feed” or giving evidence of intestinal trouble could be obtained from the keeper. The three excluded cases had invaginations in the middle and lower small intestines but not at the cecal valve. Volvulus did not occur in the Carnivora.

A paradoxure (Paradoxurus hermophroditus) died as the result of a strangulation of a six-inch knuckle of gut which had passed through a hole in the omentum. The animal had not been eating well for a month but gave no signs by which this ileus could have been diagnosed. Perhaps it had existed for sometime but only shortly before death had swollen sufficiently to cause obstruction.

Having excluded a doubtful invagination in a small rodent there remains an interesting though somewhat obscure case in a porcupine (Erethizon dorsatus dorsatus). This animal suffered with an acute hemorrhagic and catarrhal enteritis while the colon seemed free of change until the rectum was reached. Here was a stretch of a foot with the purple, lusterless but translucent 215appearance of a strangulated intestine although no involution or twisting remained. This was looked upon as a volvulus which had untwisted a few hours before death.

Intussusception was seen only once in the Ungulata, a tapir (Tapirus terrestris) with chronic enteritis. Here the ileum had passed into the colon for a distance of nine inches, it being much swollen and congested but not gangrenous. Its condition warranted the idea that the process was antemortem but a peritonitis had not arisen, death having occurred from the slight extra shock in an animal suffering with chronic malnutrition. Volvulus was encountered three times, two deer and a zebra. The last was the animal already described that carried such a heavy load of sand in the gut tract, a factor in the production of the twist probably although this might have been aided by a fibromyoma of the colonic wall. The location of the volvulus in this order was twice in the dilated descending colon, the third in the jejunal area. This last was a twist which resembled an internal strangulation because of the intricate knot-like windings of the small bowel.

The marsupials present two interesting cases. A rock kangaroo (Petrogale pencillata) had chronic gastric ulcerations with local peritoneal adhesions which apparently obstructed nearby coils of intestine so that they became inflated and twisted over. An opossum had a volvulus of the stomach which performed one and a half turns from left to right; its protocol follows.

Common Opossum ♂ (Didelphys virginiana). Ileus. One and one-half complete volvulus turns of stomach on duodenum. General condition fairly good. Abdomen quite prominent, a condition found to be due to great dilatation of the stomach which occupied the whole anterior part of the abdominal cavity. The organ is blue and the vessels stand out. Postmortem changes are occurring everywhere favored by the obstruction to the circulation. The dilated stomach has undergone a volvulus upon the third part of the duodenum making one and a half turns. The spleen lies upon the right side well below the liver; it is swollen, soft and deep purple. The duodenum in its upper half takes part in the dilatation and beginning gangrene. The pedicle of the 216twist is made of the duodenum, esophagus, edge of the mesentery and the middle part of the pancreas; the end of the tail of the last is gangrenous. There is no apparent obstruction lower down to explain the twist of the stomach.

Among the Aves the following cases only are worthy of report. A parrot (Melopsittacus undulatus) was found to have a tightly packed mass of worms in the end of the duodenum above which the bowel was distended, elongated, doubled on itself and of a deep red color; below this the small intestine was empty. A closely similar condition was found in a Screech Owl (Otus asio asio) the obstruction occurring just above the end of the small gut. A Sparrow Hawk (Falco sparverius) had an invagination two cm. in length, a short distance above the end of the small intestine. No peritonitis existed but the presence of an acute enteritis helps to explain the intussusception.

Hernia is not a common occurrence among the lower animals but our experience is instructive in two particulars, to wit, its absence in the orders preceding the Rodentia and the frequency of the traumatic variety. There being no general remarks to be made upon the subject, it seems well to give a summary of the findings in each of the seven cases.

A Western Fox Squirrel (Sciurus rufiventer) showed a diaphragmatic defect on the right side, a rounded opening with smooth edges, through which a loop of intestine had passed, entering behind the liver and reaching into the pleura as high as the pulmonary apex where it was adherent; this was probably of long standing. Two more loops were found wedged in the diaphragmatic hole, one of which was gangrenous.

An Indian Antelope (Black Buck) (Antilope cervicapra) presented an irreducible incarcerated but not strangulated umbilical hernia. The peritoneum was fused 217with the aponeurosis at the ring but the gut was not adherent at this point while it was attached within the sac outside the muscle, thus forming the incarceration. Apparently the sac had dissected between the muscular layers for it could be followed for several centimetres in some directions. A Hog Deer (Cervus porcinus) had apparently suffered an injury in the flank for at one point the muscles were irregularly cicatrized and a rent was present through which several loops of intestine and a band of omentum had escaped, being adherent to fascia. No injury to the skin was apparent.

Another Indian Antelope showed a clean traumatic rupture of the muscle and peritoneum in the right inguinal region without penetration of skin. An acute hernia had occurred which was lightly adherent to fascia and an acute peritonitis was beginning. The bowel was however not strangulated.

An aoudad (Ovis tragelaphus) seems to have suffered an injury by a pointed object (horn?) just to the right of the ensiform cartilage for at this position there is a circular hole, with smooth healed edges, in the aponeurosis, permitting the emersion of a peritoneal sac containing omentum. All parts were adherent but no acute inflammation existed.

What may have been a hernia or a relaxation of the transversus perinei was observed in an Undulated Grass Parrakeet (Melopsittacus undulatus). A bulge about the size of the finger end was seen externally, beside and behind the anus. This proved to contain several loops of bowel and a mass of fat.

A lateral abdominal hernia was seen in a Barbary Turtle Dove (Turtur risorius). It consisted of a peritoneal sac and two loops of intestine. This protrusion, while firmly fixed in its unnatural position, was in no way constricted.

Prolapse of the rectum may in a sense be looked upon as a hernia or at least as a relaxation of the anal and perineal muscles with protrusion of parts normally situated intracorporeally. Although not frequent it has been incurable in the animal, as it frequently is in man without operation, a measure we have not adopted. Just what determines weakness in the pelvic outlet is entirely obscure for indeed we have seen here wounds and inflammations of the perineal area without prolapse of the rectum and in none of the cases of prolapse did the pelvic floor seem injured or diseased. It is but speculation to blame the annular muscles of the anus. Tenesmus, or at least reasons for this straining action, have been sought, with the result that in our cases lesions of the egg-laying apparatus in birds and enteritis in mammals have stood out most prominently. In no case have hemorrhoids been encountered nor has a tumor pendant from the colonic mucosa, drawn the bowel toward the anal opening. It might be added parenthetically here that hemorrhoids are practically unknown for quadrupeds, Hutyra and Marek failing to mention them independently and only one reference being found in the Jahresbericht fur Veterinär Medizin (Schmidt 1914–169); this case is more like angioma than hemorrhoids. If tenesmus be active in the production of rectal prolapse then it would have to be assumed that this straining effort can be induced by enteritis since eversion of the rectum has occurred with this disease in the absence of colitis, the condition usually expected in the presence of tenesmus. The thirteen cases have been seen in Mammalia, 8, (Carnivora, 2, Rodentia, 1, Ungulata, 3, Edentata, 1, Marsupialia, 1) and Aves, 5, (Passeres, Picariæ, Striges, Psittaci and Galli each one). Three mammals had enteritis, one had foreign bodies in the bowel and one had many ascarids; three had no demonstrable or suggestive causes. Two of the five birds 219had enteritis high in the tract, one had uratic calculi in the cloaca, and three had trouble in the egg-laying apparatus: one too large an egg, one a broken egg and one a salpingitis.

It is almost certain that in a human pathological service of fifty-five hundred autopsies, one or more diverticula of the Meckel variety would be encountered and perhaps several of other kinds. In our material only pouchings or false diverticula of the colonic wall are recorded, and our personnel has often spoken of the absence of these gross abnormalities of the alimentary tract. The two cases, notes of which are given, are instances of hernial pouchings of the colonic mucosa and serosa, a condition which is well known in human medicine. It may be said to occur in two varieties, one in which the pouchings have heavy walls formed by a thickened mucosa, muscularis and peritoneum and one in which the bulgings have delicate walls, then being small herniæ of the inner coats through rifts in the outer. Such a division is probably unnecessary or misleading since the latter may be only a forerunner of the former. However the clinical evidence of the simple variety is scanty and may be little more than constipation while the peritonitic variety gives a clinical picture of pain, constipation and a mass in the left abdominal area, then known as diverticulitis or pericolitis sinistra. In these cases the colon is much distorted by the irregularity of its mucosa and by inflammatory thickening of the muscularis and serosa. Diverticula arise from defects of the muscular coat, or secondarily after inflammation or prolonged constipation, by weakness of muscle, or as hernial protrusions around the entrance of blood vessels where the muscle is thin. Such sacculations permit feces to collect and continue the inflammation, thus further weakening the gut and producing constipation, the whole vicious cycle being favorable 220to the formation of more sacculations; coproliths may form in the diverticula. The two monkeys now reported seem to have varying grades of the same condition, a long standing colitis with diverticula, constipation and the collection of inspissated feces in the sacculations. These animals did not have hemorrhoids.

Black Ape ♀ (Cynopithecus niger). Coprostasis. Coproliths in diverticulum. Chronic colitis. Cor bifida. The large intestine is of the same calibre as the small intestine should be when not distended. The sacculations as seen before opening the organ are salient, forming distinct pouches. In one or two cases they are so pronounced as to constitute diverticula 7 cm. long. In two instances the serosa at the fundi of these diverticula is markedly hyperemic and very thin. In many cases the sacculations contain coproliths. The wall of the organ is distinctly thickened, puckered, inelastic and opaque. Mucosa is thrown up into coarse rugæ.

Japanese Macaque ♂ (Macacus fuscatus). Chronic hypertrophic colitis. False diverticula of colon. The large intestine contains a moderate quantity of quite constipated feces. The serosa is smooth. The wall shows at several stretches enlargements of the normal sacculations, forming false diverticula. The wall of the gut in these herniæ is thinner than in the surrounding parts; no ulcers exist; no local peritonitis is present. The mucosa everywhere is irregular in thickness, less translucent than normal and thrown into irregular rugæ; tenacious mucus covers it. No ulcers.

Only one tumor was observed in the mammalian intestinal tract proper. Dasyure (Dasyurus maculatus) Adenocarcinoma of the intestines. On postmortem there was a pale diffuse thickening of the coats of the small gut over a large area; numerous soft, light yellow, sharply circumscribed, elevated (like secondary tumors) nodules in the liver and spleen, and a pea-size whitish nodule around a bronchus in the right lung. Histological section of primary growth not made but a cross section of the intestine in the vicinity shows an adenomatous change with considerable increase in the connective tissue. The nodules in the liver, spleen and lung and the appearances of the abdominal lymph nodes, found microscopically, are precisely similar. They consist of irregularly arranged 221epithelial nests and distorted acini, around which are sharply outlined spaces, filled with the remains of degenerated blood or a granular material. The metastases are always sharply outlined.

Aves supply three papillomata which are interesting in that one occurred in the proventricle, and two grew in the duodenum in the vicinity of the upper biliary opening and presented within the lumen soft masses which, while not occluding the passage, offered some little obstruction as indicated by a slight distention above their location. In two, carefully studied, no indications of parasites or of cancer could be found. The birds concerned were an amazon, an owl, and a rhea.

SECTION VII THE ALIMENTARY TRACT, PART 2. THE LIVER — Fat Deposits. — Amyloid Deposits. — Degenerations. — Acute Atrophy. — Hepatitis. — Necroses. — Abscess. — Cirrhosis. — Gall Stones. — Inflammation of the Biliary System. — TUMORS.

A consideration of the liver is anatomically and physiologically the next step in the discussion of diseases of the alimentary tract. While this organ may participate in most of the pathological states of the tubal part of the system, it is comparatively seldom the primary seat of change and when damaged seems to be possessed of great accommodative and reconstructive power. This must be true, and fortunately so, since we ascribe to it the major detoxicating function of the body. Nevertheless it is noteworthy that the largest solid organ of the animal body shows a relatively low percentage of changes threatening to life. In the sense of Pearl’s method of statistics, it does not “break down” easily. In pathology it is the custom to list with great care all the changes, gross and minute, in the liver, but with a few exceptions they are secondary or incidental. They do however reflect many things, especially referable to diet and to chronic infection from the intestinal drainage area. It is in these directions that the organ will be studied in the following pages.

Anatomically the liver is situated in the right upper part of the abdomen subjacent to the diaphragm in both mammals and birds, being held in position by attachment to this transverse partition, by ligaments or folds of peritoneum, and by the other abdominal viscera. Its general relationships do not offer great variations since in all animals means are afforded for a dual blood supply and an outlet for the hepatic secretion, the bile, into the higher intestines. Naturally variations in the size of the lobes are observed and there has been considerable speculation as to their independence and association. From the standpoint of comparative pathology, little can be 223ascertained to assist in this matter unless the position of abscesses and hepatitis relative to cholecystitis have a bearing; some discussion of this will appear later. We have not observed any peculiar pathology of the lobes of Spigelius and Riedel. In so far as the size and arrangement of the organ is concerned a few general facts of significance may be mentioned.

It was formerly thought that the liver varied inversely as the size of the animal but Magnan^[23] and others have shown that the matter is not so simple. In the first place if there be an actual mathematical formula it is that the liver varies in size inversely as the surface area of the body, but this is not the whole story. It seems that the relation of size of the organ to its weight is not constant and that it is better to judge of the organic capacity by the latter. In herbivorous animals, both birds and mammals, the liver is lightest per kilo of body weight; next in weight are in order, fisheaters, meateaters, insectivora, seedeaters, fruiteaters and omnivora. There is besides this a roughly inverse ratio between the size of the liver and the length of the intestine and in the class Aves inversely as the size of the lungs also. From the immediately foregoing statements it is apparent that a bewildering variation occurs and that only rough measurements of the relative volume of the liver are available. An attempt was made in the Marsupialia, which present all the variations given, to discover if any peculiar pathology corresponded with the above groups; as it was fruitless, no change from our zoological treatment will be made.

Lobar arrangement varies from the relatively simple double avian type to the manifold lobulations of the seal or the marsupial but I can find no literature to indicate that lobes or lobulations have a direct effect upon functions. There must be a difference of blood supply for in 224certain infectious diseases like enterohepatitis and amœbiasis, the cystic and extreme right lobes are more affected than the left parts of the organ. In the bird this is not so difficult to follow since the three divisions of the portal vein, while they combine at times in an ampulla within the hilum of the liver, seem directed to certain lobes, that from the left portal seeming to point toward the right side. The avian portal system differs from the mammalian in having a large branch from the renal area, the so-called renal-portal system, pass to the liver, and by having a free anastomosis between the portal area and the caudal vena cava whereby blood from the pelvic district may pass into the general circulation without going through the liver. There is no unanimity of opinion as to the function or importance of this connection^[24] and from the data collected here there is no peculiar renohepatic pathology.

The gall-bladder is not a constant organ in either mammals or birds and indeed it may be absent or present in very closely related species (Two-toed Sloth present, Three-toed Sloth absent). When present in mammals it is usually a dependent bag while in birds it commonly lies upon the cystohepatic duct, between the liver and the last curve of the duodenum, in some varieties filling from the bottom, the inlet being guarded by a valve. This cystic duct in nearly all birds, comes exclusively from the right lobe while the hepatic duct, with which the cystic has no connection, is formed by combination within the liver of radicles from both sides. It passes to the duodenum well in advance of the cystic duct, in some birds, e.g., the Struthiones, very near the pylorus, that is on the descending limb of the duodenal loop. By this means obstruction to the biliary stream is rendered difficult. The common duct combines with one of the pancreatic outlets in most mammals but the abdominal salivary gland in 225lower animals has more often patent separate ducts or multiple ducts than it does in man. Birds have one to four pancreatic ducts separate from the biliary openings.

The gall-bladder is missing in most varieties of the following groups: pigeons, parrots, wrens, ostriches, rheas, cuckoos, toucans among the birds; most odd-toed ungulates, hyraces, Indian elephants, all deer, peccaries, three-toed sloth, and many rodents. The varieties lacking this reservoir are herbivorous in the main, true carnivores seeming always to be possessed of such a structure. Among the important herbivorous ungulates, Bovidæ, Tragulidæ, Camelidæ and Suidæ have this bile reservoir almost without exception. Because of the interest now being shown in the pathology of the gall-bladder and its passages and of the pancreas, it was hoped that evidence of definite practical value for human pathology would be at hand in our study if we divided the animals into groups with and without a bile reservoir. The result is not unequivocal but worthy of note; it is discussed on pages 238 and 255.

Microscopically the well known lobular arrangement of the liver is rather faithfully carried out among the mammals albeit the most systematic and complete architecture is to be found in the pig while the marsupial seems the most disorderly, thus resembling the avian organ. In the latter class all the parts are indistinct, the cells having an unclear outline, the tubules being intricately wound and the interlobular connective tissue being scanty and not anastomosing in a definite framework. The intralobular reticulum is especially difficult to detect. Groups of cells are often found at portal spaces; these are large and small mononuclears and granular cells, probably of the hematopoietic system. It is possible that blood formation is performed in the liver and spleen in some adult birds but such a function is denied for the mammal except under very unusual conditions of bone marrow atrophy.

226Glycogenic and fatty conservation is a function possessed by both zoological classes as are the detoxicating and bile-producing powers. However it is highly probable that urea and creatin in metabolism is not cared for by the avian liver as it is by the mammalian, judging by the researches of Paton and of Richet.

The care of fat by the liver is very well shown by examining the incidence of fatty metamorphoses through the various orders. In the first place Mammalia show a slightly higher percentage of fatty change than do Aves and should show a greater difference were it not for the large number of cases in two orders of the latter. Among mammals, lemurs, rodents and marsupials store fat in the liver more than other orders but in the second and third, it is chiefly the carnivorous varieties that have this property. Just why the slothful herbivorous lemurs should be first on the list is not evident especially since the grain-eating Ungulata are least apt to present fatty livers. With this exception, mammals with plentifully available hydrocarbons in their diet are most apt to show its deposit in the organ under discussion. Among the birds the gallinaceous varieties stand far ahead of all others, the passerines following next. Galli show the condition in association with acute infections, chronic diseases and in health. Unless there be distinct reason for it at autopsy, it may almost always be said to be normal. Passeres, especially the smaller forms, frequently come to autopsy with such excessively large livers, and indeed with a very large pad of abdominal fat, and nothing else, that one is compelled to look upon this overburdened organ as incapacitated by the deposit. These two orders increase the percentage value for the birds. Striges, Anseres, and Accipitres also show a good number of cases but there is among the Aves no such clear relationship 227between food fat and fat infiltration as may be found in the Mammalia.

Amyloid deposit is reported with reasonable frequency in domesticated animals, causing in them a fairly definite entity, being as usual related to the effects of long continued or repeated infectious disease. Wild animals suffer from this condition but rarely and therefore to our few cases will be given a short discussion separately. An Indian Paradoxure (Paradoxurus niger) had patches of amyloid irregularly distributed through the organ. The animal had a carcinoma of the head of the pancreas, an obstructive biliary cirrhosis in a state of atrophy and a chronic nephritis with arteriosclerosis. There was nothing peculiar about the distribution of the deposit as there was in the next case, a Badger (Meles meles) where amyloid was found around the interlobular vessels and extending in the lobules along their canaliculi. This latter case seemed without cause and we have considered it a primary amyloidosis, the spleen, heart muscle, kidneys, intestines and other structures being affected. (See Fig. 7.) A third mammalian case concerned a Dasyure (Dasyurus viverrinus) which showed distinct intralobular collections. Its cause was a chronic suppurative process in the jaw bone.

Avian livers are somewhat more prone to show amyloid deposits, eight cases being on record. Four occurred in the Passeres, one each in Columbæ and Impennes and two in Anseres. Three were associated with chronic infectious disease and two with well established nematode parasitism. The remaining three, classed as primary, were not related to any other lesions, in two the amyloid liver being the only finding.

The next abnormal deposition related to the physiology of the organ is blood pigmentation. Normally hemic pigment is dispensed with very rapidly but under unnatural 228conditions it accumulates. In only one order is there any noteworthy percentage of hemosiderosis, the carnivores, the remainder showing a very trifling incidence.

Going further into the physicochemical alterations of the liver brings us to consideration of those changes known as degenerations—parenchymatous, fatty, hydropic, hyaline, all of which we shall group under one heading. They occur in a great variety of conditions and do not appear to be specific, nor as the records are analyzed do they appear to occur preëminently in any one disease of the lower animals. The percentages are however higher for orders and families whose diet contains relatively more protein, carnivores, the higher marsupials, accipitrine, and wading birds.

A very important degenerative disease of the liver is acute yellow atrophy or, better expressed, acute degenerative atrophy for it is a total destruction of the whole or large parts of the parenchyma. It is apparently toxic in origin being related to the toxemias of pregnancy, to certain organic and inorganic soluble poisons; some cases arise without discoverable cause. We have seen no cases in the mammal but two in birds. Both were females, one in active ovulation, while the other had no related pathology and the condition of the ovaries could not be determined since they had been destroyed after death by rats. The macroscopic and minute anatomy offers nothing new. Jaundice was present but not intense.

True inflammatory lesions are to be defined as some form of parenchymatous change to which are added congestion, infiltration of round or polynuclear cells, stagnation in the bile ducts or perhaps actual degeneration of 229their lining cells. It seems necessary to stipulate these things because in the chronic forms, usually called cirrhosis, it is necessary to have all of them, plus efforts at regeneration, in order to determine it as a chronic progressive process. Acute hepatitis is a rare condition in mammals except when it is combined with septicemia or severe enteritis. In birds on the other hand the liver is, aside from the intestinal wall, perhaps the most frequent seat of pathology in the abdomen. This is because of its almost constant involvement in infective enteritis, and in such conditions as fowl cholera, fowl typhoid, coccidiosis and cecal amœbiasis, all of which we have sporadically. When one searches for special distribution among the orders, only one of them stands out as having a high percentage, the Galli, an order which seems to have a very vulnerable liver.

The macroscopic anatomy of hepatitis in birds is peculiar in showing a definite swelling with spots of gray or yellow color, sometimes coalescing to form irregular areas. These are much more definite than in the mammalian organ where swelling and hemorrhage are the commoner findings. These pale spots are of two origins. They may be focal necroses of the hepatic cells, with or without circumferential congestion or hemorrhage to make them stand out. In amœbic, coccidial and typhoid livers such is the type of change. In septicemia and cholera, the mottlings are made up of increased interstitial mononuclear areas, with blood cells and shadow cells numerously present. I have seen what was in all probability a stage of repair after both these kinds of change. In the former, regeneration seemed to take place from adjoining liver cells, there being in the section no evidence of increased bile ducts to make new hepatic cells. It seemed also that phagocytes were derived from blood cells and not from Kupffer’s cells. In the infiltrative lesion disappearance of the liver cells from the groups leaving compressed and deeply granular remnants was all 230that could be determined. Regeneration seemed to be progressing in the manner just outlined.

The degenerative and infiltrative areas of acute hepatitis are simulated by focal necroses in livers not the seat of a general hepatitis from which they can be differentiated only by the microscope. These small areas of local tissue death are quite common in all pathological processes but are most common in the liver, possibly because of its exposure to toxins from the intestine. Their exact origin is not determined, various explanations being given. The somewhat distinct distribution in mammals versus that in birds may help in the final decision. In the former, focal necroses are more often encountered midway in the anatomic lobule and around the central vein whereas a perivascular location seems the usual position in the bird.

Massive necroses of the liver may be of considerable importance in veterinary medicine. They take their origin in several different ways. The commonest in our records are those due to cecal coccidiosis and amœbiasis (quail disease and blackhead) while from the primary seat of these two infectious diseases, the cecum, may originate the virus of nonspecific hepatic necroses. We have observed several birds, passerine, psittacine and gallinaceous, which at autopsy showed a distention of the cloaca, ceca, and lower small intestine with urates and slime but no mural inflammation and a large area of necrosis in the liver. This suggests perhaps a “white diarrhœa” but it did not occur in epizoötics and other morbid anatomy of this specific disease was absent. These frequent instances of association between the colonic area and the liver seem to suggest the transfer of necrotizing organisms, just as amœbæ travel, and to indicate measures to clean out the tract when birds become “plastered.” Massive necroses also arise from mould disease, and from 231infection with the necrosis bacillus, emanating from nearby infectious foci, or via the normal passageways from the intestine. Massive areas of degeneration may form by the coalescing of numerous foci, in any septicemic disease.

In man, amœbæ, flukes, cestodes and biliary tract infection are the commonest causes of purulent collections within the liver. In the lower mammals parasites play practically a solitary rôle at least as the major influence in localizing the collection, bacteria from the intestine doing the rest. We have one case of massive abscess in a porcupine suffering with septic pneumonia, the suppuration in the liver being due to the colon bacillus, the general septicemia probably being from distemper. Monkeys have shown more abscesses than any other order, three being observed. One was due to infestation with trichocephalus which had apparently penetrated from the colonic wall into the liver through adhesions formed between these two structures. Another seems certainly amœbic but these protozoa could not be found, while the third followed an ulcerative enterocolitis of unknown cause. Two cats were seen with parasitic abscesses; one harbored Distoma or Clonorchis sinensis, the other a nematode of ascaris type.

The topographic distribution of these six hepatic abscesses was interesting. The position of the abscess is not mentioned in one case but of the remaining five three were entirely in the right lobe, one had the major lesion on the right side and smaller separate abscesses spread over the organ, and one with about equal distribution in all lobes. All three confined to the right side were solitary.

Abscesses of considerable size are not met with in the bird as in the mammal perhaps because the former does not form real pus, necroses developing instead.

232Congestion of the liver is a matter of small importance from the standpoint of pathology unless it be of sufficient duration to cause cyanotic atrophy and induration. However the facts that congestion of this organ occurs three times as often in the mammal as in the bird and that vascular cirrhosis has not been seen in the latter class, are interesting and noteworthy. In addition ascites of hepatic origin has not been seen in the birds. The explanation for this lies in the rich anastomosis between the intestinal area and the caudal vena cava so that the blood does not have to pass through the liver to reach the heart. This arrangement would reduce the back pressure in passive congestion and relieve the liver in the congestion due to toxic or inflammatory distention of small vessels.

The chronic inflammations or so-called cirrhoses of the liver have been subjected to a great deal of study and many theories have been expounded as to their cause and classification. Here is not the place to discuss the academic question of nomenclature but rather to adopt an acceptable working classification and to analyze our material thereon. A cirrhosis is a chronic inflammation of the liver indicated by increased connective tissue with evidences of degeneration and attempts at regeneration on the part of the hepatic cells. Certain cases of increased connective framework fail to show the last two features and, since they must be grouped near the cirrhoses because of the prominence of connective tissue, they are called fibroses, perilobular in type. Among the instances carrying out the full stipulations are livers with evidence of a perivascular fibrosis and obstruction, to which are added degeneration and regeneration of the lobular margins; such are PORTAL CIRRHOSES in human medicine associated with passive congestion in the intestinal area, and ascites. In a second variety, fibrosis seems to succeed upon obstruction to the biliary lumina or upon peribiliary 233inflammation, BILIARY CIRRHOSES. The effects of this are to dam back bile with the production of varying degrees of jaundice and for the inflammation to spread into the lobules, thus distorting their internal architecture; this form is therefore unlike portal cirrhosis which alters the size and shape of lobules as a whole. Fatty change is very prominent in certain cases and it has been a custom, perhaps without warrant, to put such livers into a separate group. It may be that they represent a different chemical process. When there exists for a long time a venous stasis in the liver, necrosis is apt to occur in the cells subjected to pressure and the absence of fresh blood. This gives rise to a “nutmeg” liver upon which may succeed a definite perivenous fibrosis.

This then is a working classification of the hepatic cirrhoses. Perhaps many slightly differing varieties might be constructed but this grouping will permit comparison and contrast with human cases, and with instances in the various orders. Because of the relatively small total, thirty-two, it is perhaps unwise to attempt any conclusions as to distribution but it is certainly noteworthy that twenty-six occurred in mammals. This means 1.6 per cent. in mammalian autopsies against .2 per cent. in avian. Among the former class the carnivores stand at the head of the list, followed in order by the marsupials, ungulates, primates, and rodents.

Carnivora have shown a few typical portal cirrhoses from a pathological standpoint but only one, in a badger (Taxidea taxus), was combined with the classical picture of intestinal hyperemia and ascites. Two of the cases were combined with chronic enteritis which may, of course, have been secondary but there was also a hyperplasia of the spleen which bespoke some grade of infection. None of the four showed involvement of the biliary tract. One animal, a skunk (Mephitis mesomelas), was jaundiced; it had anemia, nephritis and enlarged spleen but no intestinal inflammation; perhaps the associated anemia 234may have been responsible for the pigmentation. Biliary cirrhosis occurred in two Carnivora, in both associated with enlarged spleen and nephritis. One showed jaundice and the other, with a huge liver from congestion and interstitial infiltration, had a small ascites. Fatty cirrhosis was diagnosed in a raccoon but this is viewed with some reservation because this animal easily stores fat and in this case it may not have been a part of the process. In none of the foregoing cases did parasitism enter into the causation of the change and I shall always specify when such a factor was probable. The only vascular cirrhosis in our records occurred in a Gray Wolf incident to a longstanding myocarditis (Gray Wolf, Canis lupus mexicanus, Myocarditis, Adenomatoid goitre, Chronic gastroenteritis, Vascular cirrhosis of liver, Subacute diffuse nephritis, Edema of lungs, pericardium, and peritoneum). Two examples of perilobular fibrosis appeared in this order, a raccoon (Procyon lotor) and a paradoxure (Trichosurus vulpecular vulpecular). The only noteworthy feature was, in the former, a very marked biliary stasis on the lobular margins and in the connective tissue; this animal was not jaundiced.

Ungulata are normally well supplied with definite interlobular strands which, in a few varieties, completely encircle the lobule but always show as clear fibrous septa going out from the portal areas. This richness of connective tissue renders more difficult a decision of increase so that unequivocal degenerations and regenerations with inflammatory changes have been demanded as criteria for cirrhosis. It has been recognized that cattle get a definite increase in their interstitial tissue without serious reaction in the parenchyma. With the knowledge of these facts in mind it has been possible to detect two distinct portal cirrhoses, two biliary cirrhoses and three perilobular fibroses. It is however evident by examining the rest of the autopsy notes that the chronic inflammations have had with one exception, little influence on 235the animal’s life and death and the associated pathology is not instructive in etiology. One old deer with the definite portal type had ascites and intestinal hyperemia which hastened his end.

The type of cirrhosis in the marsupial is progressively inflammatory and of the biliary variety. In two of the three cases there was active infection somewhere in the body, one a long continued streptothricosis, the other and more important a choledochitis with involvement of the pancreatic head. The third case showed a nephritis and a pericholedochitis and pericholecystitis. In all three there was definite evidence of biliary obstruction within the liver and in the occurrence of general jaundice.

Monkeys have presented one portal, two biliary, and one perilobular cirrhoses. The London Garden reports a cirrhosis with gall stones in a Chimpanzee. The case of the Barbary Ape is so good that it is quoted in brief.

Barbary Ape ♀ (Macacus innuus). Found dead. Never known to be sick. On exhibition nine years. Acute dilatation of stomach. Acute gastritis. Portal cirrhosis of liver. Acute parenchymatous nephritis. Chronic passive congestion of lungs. Chronic splenitis and perisplenitis. Ascites. Mild passive congestion of abdominal circulation. On opening the abdomen a dilated stomach occupies most of the anterior part, displacing the intestines downward and backward. The upper lobes of both lungs are uniformly deep red, soft, collapsed, subcrepitant. Subclavian vessels—veins distended with red clot, arteries with small amount of chicken fat clot. The heart is dilated on the right side, filled with currant jelly clot. The liver is small, surface hobnailed, edges rough, consistency tough, color brown. Section surface glistening, moist, granular and opaque, mottled by irregular brown areas separated by paler brown intercommunicating bands. Gall-bladder is small, contains viscid yellow bile and duct is patulous. Areolar tissue about the bile ducts is thick and opaque, the duct wall itself is thick and yellow. Gall-bladder tightly attached to capsule of liver. Spleen is slightly enlarged, soft and tough. Capsule is smooth, opaque and thickened on gastric surface. The trabeculæ are prominent, pulp mottled gray-red, few recent hemorrhages. Capsule of the kidneys is smooth, strips easily leaving a smooth brown surface with dilated vessels. Organ is soft. Section surface is glistening, striæ wide and indistinct, glomeruli faintly visible. Microscopic section of liver shows high grade of fibrosis almost entirely confined to portal areas with a marked increase in bile ducts although no place is found where these bile ducts are running 236into lobules suggesting attempt at regeneration. Liver cells show high grade of fatty degeneration in some places, whole lobules being necrotic. There is no pigmentation and connective tissue is fairly rich in cells. Fibrosis quite well advanced. Cells about equally fibroblasts, round cells and polynuclears. Bile ducts very well preserved and cellular infiltrate rather less directly around them than at other parts of connective tissue. The section of kidney shows moderate congestion, granular and vacuolar degeneration of epithelium generally distributed except in proximal tubules where there is swelling and desquamation. Detritus present in tubules and capsular spaces. Tufts swollen.

The biliary forms of Primates were associated in one case with an undetermined parasite in the bile channels, in the other with tuberculosis and chronic enteritis. In all the cases the relative inconspicuousness of bile in ducts or in cells is worthy of mention. The perilobular fibrosis in a small cebus was trifling in extent but was associated with considerable round cell infiltration in isolated areas; there was also nephritis, splenitis, and enteritis.

The only representative of the rodents is a capybara (Hydrochœrus hydrochœrus), their largest variety. This case was originally described as a typical Lænnec or Pictou cirrhosis but I now class it as a portal form. The distinct insular arrangement of the lobules, the failure of involvement of the bile channels and the ascites are reasons for the present decision. The animal suffered also from tuberculosis (not in liver) and myocarditis.

The Indian Elephant, “Bolivar” (Elephas indicus), an old specimen, is the only member of his order to show cirrhosis. It may be considered as a senile process in part but the extreme distortion and compression of the lobules press the conclusion that it was a progressive inflammation.

Fig. 18.—PORTAL CIRRHOSIS OF LIVER IN ATROPHIC STAGE. BARBARY APE (MACACUS INNUUS). THE DILATATION OF THE STOMACH ALSO SHOWS IN PHOTOGRAPH.

Fig. 19.—ATROPHIC PORTAL CIRRHOSIS OF LIVER. INDIAN ELEPHANT (ELEPHAS INDICUS).

237Aves fail to show lesions which could be called portal cirrhosis, five of their six cases being biliary and one fatty with signs of continued infection. The macroscopic anatomy of the avian liver with chronic fibrosing hepatitis is fairly uniform and suggestive. In the first place it is grossly nodular, lumpy, not finely granular or “hobnailed.” The sensation to the finger is resilient rather than tough. The color is variable but green and dull purple are the usual shades. On section no peculiarities present themselves unless it be that one can find pale spots on a dark background, which may correspond to the mammalian connective tissue strands. Microscopically the increase of cellular groups at portal spaces and the extensive growth of connective tissue between the liver columns are the noteworthy features. There is nothing in mammalian cirrhoses to compare with the intralobular growth of fibres in birds. There is of course no regularity so that the degree of replacement or necrosis of parenchyma is hard to estimate. Bile ducts do not proliferate but seem, once obstructed and surrounded, to succumb to the inflammation. The six cases in birds are: Psittaci, 3, Galli, Anseres, Struthiones each one. The cases in the last two orders were associated with parasites, to which bacteria or toxin may have been added. It is interesting to note that the two frankly progressive obstructive biliary cases in the parrots showed general jaundice.

It was formerly customary in many quarters to speak of atrophic and hypertrophic cirrhosis. Now it is generally thought that any form will be large or small as growth and regeneration on the one hand, or contraction, atrophy and degeneration on the other, may be predominant at the time the organ is seen. It is perhaps misleading to judge by our notes of what happens, but it is curious that in the thirty-two cases, the pathologist could state only in seventeen instances that the liver was larger or smaller than normal. This means therefore that the liver of cirrhosis need not deviate greatly from its customary size. Nine of the seventeen times the organ was considered smaller than normal, eight times it was greater. These variations did not strictly correspond to type, but the portal form, frequently called atrophic, was more often small than was the biliary form.

238Gastrointestinal disease accompanied cirrhosis in fourteen instances. Nephritis was present nineteen times. The spleen was enlarged six times, in all of which definite evidence of infection existed in the body. Choledochitis existed four times, twice with biliary cirrhosis, twice with perilobular fibrosis; cholecystitis existed twice, once in a monkey, and once in a bird with parasites. Pancreatitis was seen in three biliary cirrhoses and once in a perilobular fibrosis.

The relation of the existence of cirrhosis to the presence of a gall-bladder is interesting. Among the thirty-two animals twenty-one have gall-bladders, eleven have not. The exact number of animals in our whole list with and without this structure, unfortunately cannot be given with exactness. As nearly as I can figure it out, sixteen per cent. of our animal posts have been on varieties without a gall-bladder, eighty-four per cent. with it. This would make the absence of this reservoir a factor favoring the development of cirrhosis since one-third of the cirrhoses are in groups devoid of this bag, yet these same groups supplied only one-sixth of the total postmortems.

Our experience with concrements in the biliary system is limited to six cases which can be detailed in brief.

American Beaver ♀ (Castor canadensis) showed a soft purplish liver with groups of tortuous yellow lines; these prove to be groups of hepaticola with fatty degeneration around them, but successful regeneration is going on; bile ducts are not seriously involved over any great part of the organ; the bladder is distended greatly with thin, yellow-green fluid; duct is not patulous; common duct narrowed at middle and above this constriction lies a small concrement; bladder contains two large and several small pale yellow-green friable stones; mucosa injected and covered with mucopus; the pancreas is not affected.

American Beaver ♂ (Castor canadensis) shows a slight bile obstruction and pigmentation through the liver but no pus or cirrhosis; bladder is collapsed containing only a little limpid brown fluid; wall is slightly roughened but not opaque; there is a blue-black stone 1.5 × 1 cm. free in the cavity; duct patulous; pancreas and intestine not affected.

Brant Goose ♂ (Branta bernicla glaucogastra) liver shows slight fatty change; bladder much distended, contains twenty-six small, quite 239hard, greenish stones; one is impacted in the cystic duct which is not patulous.

Pigtailed Macaque ♂ (Macacus nemestrinus) shows a normal liver; bladder contains a small black concrement, very hard, no cystitis.

Polar Bear ♀ (Ursus maritimus) showed a chronic cholecystitis and cholangitis, the stone (?) in this case consisting of a solitary, black, friable mass, six mm. in diameter.

Mongoose Lemur ♂ (Lemur mongoz) showed a normal liver; bladder of about normal size but the duct can be forced only by considerable pressure; there is a small stone and a granule in the tortuous cystic duct; no cholecystitis.

The specimens that are preserved show these to be chiefly inspissated bile, those from the first beaver and the goose being the only ones to rise to the dignity of gall stones; it would seem that there was plenty of opportunity for calculi to form in the bladder of this beaver. In no case is there a cholangitis or cirrhosis dependent upon cholelithiasis.

While stones have been shown as infrequent there is a condition of the bile which may be quite important. In Passeres, Accipitres, and Striges one frequently sees a very dense inspissation of the bile both in the cystic area and in the lesser independent bile duct. This need not be, indeed usually is not, associated with hepatitis or cholecystitis. There is no one thing more common than another in relation with it but the diagnoses most often made are enteritis, distention of the proventricle and gizzard, and constipation.

The biliary tract from its origin in fine intrahepatic radicles to the bladder and to the end of the common or intestinal ducts is the seat of many inflammations both acute and chronic, but since they are supposed to lead to damage to the liver and pancreas and to the production of gall stones, it is well to consider the system as a whole. As a matter of fact separate analyses of cholangitis, choledochitis and cholecystitis do not reveal different figures for each or for different orders. The vulnerability 240of this tract is found to be directly as the percentage of cirrhosis, to wit, the carnivores stand first, then the marsupials, ungulates, Primates and rodents; among the birds the order is Accipitres, Anseres, Struthiones, Psittaci, and Galli. It is difficult in most instances to evaluate the various possible etiological factors, but, due caution being exercised, gastrointestinal inflammation could be held responsible in seventeen of the total of fifty cases. In twelve of the seventeen this process was wholly or largely in the duodenum. The next factor was general infection, at the head of which pneumonia and “distemper” occupied about equal places. In marsupials, the streptococcal and streptothrical infections to which these animals are susceptible, was the prime factor. This group almost always has definite signs of stasis both in the liver and, as indicated by jaundice, in the general tissues. Pancreatitis was present in seven of the fifty cases and in five of the seven, enteritis was also found. Common duct stones were not observed. I shall have something to say about pericholangitis and pericystitis under the head of pancreatitis.

The liver presents a good share of the tumors appearing in solid viscera but, with the exception of a few points, they offer little of interest. In the first place three angiomata have been seen and while they may not be tumors in the accepted sense of the word, may be considered briefly. A single cavernous angioma was seen in a goose. It occupied a large part of the right lobe but did not seem to affect mechanically the function of the organ since conditions wholly foreign to the liver were the cause of death. A leopard presented several small groups of telangiectatic angiomata lying mostly at portal spaces, a few also under the capsule. The liver of a thrush was likewise scatteringly beset with small angiomata. The original 241notes and recent examination do not reveal parasites or perivascular sarcomatous change.

Simple adenomata were observed in a woodchuck (Arctomys monax). This diagnosis is made with the appreciation that nodular regeneration of the liver after damage and in cirrhosis sometimes suggests tumor, but with adenomata an increase of supporting framework may occur. The liver of this animal presented numerous .3 to 10. cm. irregularly spherical, encapsulated, firm or slightly resilient, brown masses which under the microscope consisted of large pale vacuolated cells in columns or strands not connected with bile ducts. The last feature speaks in favor of the diagnosis of adenoma. The damage to the organ was probably considerable and the portal circulation must have been impeded since passive congestion and ascites were present. Enteritis and nephritis seemed the causes of death.

Adenomata or fibroadenomata of bile duct origin were seen in four animals, a Red Fox (Canis vulpes pennsylvanicus), a Gray Fox (Canis cinereo argenteus), a Jaguar (Felis onca) and a Common Deer (Mazama virginiana). The first two present similar pictures, pinpoint to 8. mm., gray, well outlined areas some of which are clearly cystic, others opaque and more solid. In the first fox a larger mass was found near the hilum. Careful study and consultation has failed to discover parasites in these cases, although their presence was strongly suspected, so that we were forced to conclude, in view of the rather typical microscopic picture, that they are adenomata of bile duct origin. Their scattered distribution, but with a tendency to be more numerous beneath the capsule, corresponds with a human case just brought to my notice. The mass in the liver of the deer was single and resembled an infarct, with cysts exposed by cross section. This tumor was found on the diaphragmatic surface of the right lobe.

242Tumors of an atypical, therefore malignant, epithelial variety were found four times, in an Alpaca (Lama pacos) and three parrakeets; these birds are very prone to have all kinds of tumors. The records of the first animal could not be as satisfactory as might be desired because of an advanced state of decomposition but there was a carcinoma-like growth of the gall-bladder area and a large hard alveolated tumor occupying one-half of the liver. The colon had been involved by the former, with perforation. Two of the parrakeets showed a simple carcinoma with well developed fibrous tissue bands running in all directions through the large mass. The whole growth was comparable to the usual picture of these massive tumors when they are primary in the liver. All these three cancers seem to take their origin in the liver cells but the third had such an interesting involvement of the connective tissue that its minute anatomy will be given; it was denominated adenocarcinoma sarcomatodes.

Undulated Grass Parrakeet ♂ (Melopsittacus undulatus). Section of liver shows organic capsule normal. Nothing remains of the original structure by which it might be recognized, suggestion in places of granular cells resembling liver cells being only occasional occurrences and in small numbers. Where liver cells do occur they are highly granular in various degrees of atrophy and show various grades of nuclear retrogression. Greatest part of section consists of dense, white fibrous tissue in which lymphocytes are rather diffusely placed together with large numbers of epithelium-lined spaces. These spaces are often elongated after manner of imperfect ducts but are of irregular form, have single layer of low cuboidal epithelium and richly staining nuclei. Upon search certain acini are found to have especially hyperchromatic nuclei and penetration of basement membrane. In such localities collections of epithelial cells are to be seen in plug form in lymphatics and acini of imperfect development of lumen are found. In addition to these epithelial lesions connective tissue ones are seen, occurring generally in restricted localities. The interstitial framework is seen to consist of closely placed spindle cells, some of which are especially elongated after manner of imperfect ducts but are of irregular form, directed in a definite, purposeful manner, but interlace in the whorling manner noted in fibromas. Nuclei are, however, entirely too chromatic for a connective tissue tumor. Whenever a vessel occurs in these regions its lining endothelium is always swollen and nuclei in its wall 243will be proliferated and of embryonic type. This latter condition is apt to occur in patchy manner, part of wall appearing normal and other parts containing these peripherated elongated nuclei.

Secondary tumors were observed in the liver seven times as follows: Red Kangaroo (Macropus rufus) from malignant papilloma of the stomach; Spotted tailed Dasyure (Dasyurus maculatus) from cancer in the small intestine; Dorcas Goat (Capra hircus) from sarcoma in lymph nodes in mediastinum; Raccoon-like Dog (Canis procyonoides) from mixed tumor of thyroid; Undulated Grass Parrakeet (Melopsittacus undulatus) from a brain tumor probably glioma; another of same species from a sarcoma of pectoral muscle; European Robin (Erithacus rubeculus) adenoma of adrenal (hypernephroma).

SECTION VII THE ALIMENTARY TRACT, PART 3. THE PANCREAS — Pancreatitis. — Tumors.

The pancreas, an organ functionating as a gland with an internal secretion and by pouring a digestive juice into the duodenum, remains a structure of constant anatomy throughout the zoological classes under discussion in that it is composed of compound racemose lobules whose outlets join to form large discharging ducts, and of interstitial bodies, the islands of Langerhans, without connection with the secreting acini but having some relation with the blood and lymph vessels. The organ originates embryologically by sprouts from the side of the primitive gut just below the part destined to be stomach, and from an outbudding of the common biliary duct. These two sprouts or pouches combine to form one organ, but this does not necessarily effect a union between their lumina. In some birds and mammals (Accipitres and some Ungulata) the lobes of the pancreas remain distinct during life, and the discharging tubules seem to empty only their respective lobes. However, there is no uniformity in the matter, and indeed the anatomy of the ducts is subject to very great variation despite the rather similar beginnings of the organ. Those who are interested in this point may consult Beddard,^[25] Letulle and Nathan-Larrier,^[26] and Opie^[27]; there will be given in the following pages the average findings of anatomy of the gland body and of its ducts.

The region of the pancreas in lower animals, especially those which travel constantly on four feet, is one of great activity, and the organs are more freely movable than in the human being. The only exception to the latter 245part of this statement may possibly be found in the cats and dogs, in which there are firmer attachments of the duodenum and pancreas to the vertebral column and the liver; this is brought about by the short gastrohepatic omentum and the abrupt curvature of the duodenum toward the back, under the mesenteric stalk. In the Ungulata and Marsupialia and in some Rodentia, the pyloric, duodenal, and pancreatic attachments are relatively loose, and torsion of the pylorus seems to be allowed for, since in these animals great distention of the stomach is the rule. Among the Aves the anatomy is wholly different. The birds have no attachment of the duodenum and pancreas to the posterior abdominal wall, except indirectly through a narrow strip comparable to the gastrohepatic omentum, one division of which passes to the beginning of the duodenum, the other to its end, and by a thin tail of pancreas which goes toward the spleen. The bulk of the pancreas lies in the U made by the long free duodenal loop, the two organs being covered by the serous membranes forming the middle abdominal sac. It will be seen from the foregoing that the movability of the pancreas is considerable—a highly necessary provision, because the stomach and duodenum are also movable and subject to distention by food and alteration of position during flight.

In the class Mammalia there are usually two ducts, one entering the duodenum in combination with the bile duct, the other variously above or below this common opening. As will be seen in Table 14, however, there are several exceptions to this statement, there being but one duct opening independently of the bile duct. The general anatomy is closely similar throughout this class, so I shall confine my notes to the exceptions from the general rule, especially where they seem to be of importance in the etiology of pancreatic lesions.

In the class Aves the pancreas consists usually of two or three distinct lobes lying one in front and two behind 246the cleft between the limbs of the duodenal loop, and it discharges its secretion into the duodenum by two or three ducts separately, and almost invariably above the bile duct openings. One duct always opens near the top of the distal end of the duodenal loop, near the bile duct. In the gallinaceous birds that have a bile duct opening into the duodenum near the pylorus, there is usually a pancreatic duct opening there also. In some birds a third duct passes from the body of the pancreas to the duodenum at different places along the loop. It does not seem probable that dislocation of the duodenal loop would seriously interfere with the passage of the pancreatic secretions, since the gland is so intimately related with the duodenal serosa, but obstruction to the biliary flow due to changes in position of the intestine is easier because the bile duct is separate and loose and arises from the end of the gall-bladder. The ducts of both these structures pass very obliquely through the duodenal wall a matter of importance, as will be seen when discussing the infiltrative forms of enteritis. The gall-bladder is not present in all birds, but this is probably of no importance, as the hepatic ducts are wide and run directly from the liver to the duodenum. The pancreatic ducts are short and are closely bound around by glandular tissue up to a place quite close to their entrance into the intestine.

The musculature of the gall-bladder and the ducts seems comparable in mammals and birds, and a constrictor or sphincter usually called the muscle of Oddi, is present in all but pigeons (Oddi). There may be found also muscular fibres in the major ducts of the pancreas, but they are not so heavy nor distributed so definitely as similar tissue in the bile duct walls. The mucosa of the pancreatic duct is much more folded in birds than in mammals, seemingly, therefore, more adapted to obstruction by swelling from any cause.

247Passerine birds have two pancreatic ducts usually on the ascending loop of the duodenum, or there may be one ahead of the pyloric biliary duct. The picarian varieties possess three ducts as a rule, one near the beginning of the pylorus, one near its end and a third of inconstant location. Owls have a system like Passeres, but the relation between the organ and the intestinal loop is looser and the ducts are wider. Columbæ have two pancreatic ducts in the ascending limb of the duodenum. Gallinaceous varieties have a double biliopancreatic system, a duct of each kind entering the descending and the ascending duodenal reaches, with the biliary placed after the pancreatic in each instance. Accipitres have always two and oftentimes three ducts as do Anseres, both orders frequently having the third duct opening at the bottom of the duodenal loop where stagnation can and does occur. Fulicariæ have usually three ducts.

The foregoing are the orders presenting pancreatitis and therefore those whose anatomy concerns this study directly. The irregularity in number and arrangement of ducts continues through all the avian orders which show a greater aberration from standards than do the mammals. Theoretically the birds should cast some light upon the unsettled question of the causes of pancreatitis, and as a matter of fact such a result seems to have been realized. In 1915 I published an article upon a study of this subject which indicated that acute inflammations of this organ may arise via the lumen of the duodenum and pancreatic ducts, while chronic processes were the result of periductal passage of pathogenic agents. Further study would seem to indicate that disease of the biliary tract is of importance in lesions of the pancreas since a decidedly large number of cases is found in mammals, where the relation of ducts is definitely more intimate than in birds. The work of Archibald,^[28] Deaver and 248Sweet,^[29] and Judd^[30] seem to agree with the findings upon our material. This need not be, however, in discord with the idea that acute inflammation is superficial in origin, chronic lesions deep or lymphogenic. The discussion will be resumed in a subsequent paragraph.

The amount of pancreas to be found in birds is greater than that in mammals. According to our figures the organ represents ¹⁄₄₀₀th of the body weight in the former and ¹⁄₆₀₀th in the latter. These figures are averages of a small number of instances and are not final. It is, however, obvious to casual daily observation that birds as a class have a large pancreas.

The minute structure of the organ is governed by the same general rules throughout the two classes under consideration. Birds do not have as many interstitial islands as do mammals, but they are more compact and seem more definitely constructed of coiled tubules. In so far as the internal structure of the organ is concerned there has not developed in our study pathology peculiar to any animal. The importance of the ducts and position of the organ will be discussed later.

Recognition of pancreatic disease during life is practically impossible. In human medicine the signs and symptoms are vague and inconstant,^[31] diagnosis often being a matter of exclusion. Veterinarians, except under the best hospital conditions make no attempt to diagnose pancreatic lesions but, since the improvement of surgical practice, at times operate upon cases of evident pain and distention which prove to be pancreatitis. These things were evident in a deer that I saw and that died on the following day from acute hemorrhagic pancreatitis; I made no attempt at this diagnosis, believing it to be acute tympanites. The feces were normal, according to the judgment of persons qualified to give an opinion.

249The condition of the pancreas at autopsy on animals not dying with lesions of this organ deserves some attention since it may confuse the uninitiated. If the organ be seen in its normal resting stage shortly after death, it is not difficult to recognize the condition as normal for the species. Activity is indicated by a darker or redder color and an increase of consistency. In carnivorous or omnivorous animals and birds the pancreas in this state is a body with a distinct bulky character, whereas in strictly herbivorous varieties, especially ungulates, the structure is diffusely pink and doughy. This is important since the early stages of self-digestion and decomposition assume this same character in all varieties, while later stages present a deep red, swollen, wet organ. These appearances must be differentiated from acute hemorrhages or inflammations, a distinction based upon actual local blood collections or extravasations and areas of degeneration in true disease. Oftentimes differentiation must be made under the microscope and in advanced decomposition, determination is impossible. When there is torsion of the stomach, notably in ungulates, the pancreas is often found decidedly congested. This, it seems, is due to a twist of the duodenum and passive congestion of it and the pancreas—the only simple explanation despite the apparent provision for a high degree of mobility, as already explained. The organ is nearly always mildly congested in severe grades of acute duodenitis, although it need not be pathologically involved. It is, however, noteworthy that the pancreas is an organ with a low morbidity index, especially when one considers its proximity to a structure showing the highest disease index in the body, the intestine. The succeeding paragraphs will reveal in comparison to other organs only a small number of cases of degeneration, inflammation and tumors. This has been ascribed to the freedom of blood supply and the power of tryptic digestion.

250An expression of this relative immunity to pathologic change is met in analyzing the data upon the simplest lesions, degenerations, to be expected in many states of disease. Only a small number of cases present themselves, and they are under expected conditions, namely in association with acute general infection, sometimes definitely septicemic in nature. About half of them were discovered microscopically, affecting the islands of Langerhans in vacuolization or granular disintegration. Focal necroses of the organ were met four times, three turkeys and a cockatoo. It is noteworthy that all these birds had some involvement of the liver, twice a complete acute hepatitis and twice a cholangitis. This is the more interesting since we shall learn that the liver is less often involved in avian than in mammalian pancreatitis. Hemorrhages occur occasionally in the pancreas in acute general infections and are seen in acute inflammations of the intestines; the percentage incidence with the latter is, however, very small. Pancreatic apoplexy proper has not occurred, for all the instances of large hemorrhage into the organ have been combined with changes forcing a classification of acute pancreatitis.

Pancreatitis in the acute form is divided by many writers into exudative, hemorrhagic and necrotizing, while for the chronic variety an inter- and intra-acinus form has been described. It is questionable whether it is fair in acute cases to focus attention by special nomenclature on different macroscopic pictures, unless it be for descriptive purposes solely, since there is nothing at hand to indicate that differing agents cause one kind every time. The physical findings seem to depend rather upon the speed of operation of the causation than upon its essence. Sudden obstruction of the pancreatic duct is believed to produce necrotizing processes to which hemorrhage 251may be added by digesting of blood vessels. Exudative cases seem due to extension of ulcerative inflammation, from a perforated gastric ulcer for example, to which digestive pancreatitis may be added. The interacinus chronic inflammations are usually considered as due to obstruction or infection through the biliary or pancreatic ducts whereas vascular disease produces intra-acinus connective tissue overgrowth. Analysis of the records of this laboratory would seem to indicate that necrotizing and hemorrhagic processes belong together, exudative in a class by themselves, and that chronic disease may be either interlobular or intra-acinar without regard to associated pathology. I have therefore studied our cases from this standpoint.

Pancreatitis has occurred in thirty-eight mammals and birds among the 5365 autopsies, an incidence of 0.7 per cent.; class incidence in mammals twenty-seven or 1.5 per cent.; birds eleven or .3 per cent. (Table 14.) Among the higher class all the important orders are represented, but by no means in equal degree, whereas in the birds, less than half of the orders are listed, with the important Psittaci missing, despite a high death rate.

It is perhaps well to be guarded in stating the relative vulnerability of the pancreas in various orders, but one cannot avoid the observation that Carnivora stand well in advance of the others (3. per cent. of autopsies), to be followed by Ungulata (1.9 per cent.) and Rodentia (1.7 per cent.). Nor can one fail to see that mammals have inflammations of this organ five times as often as do birds.

255Further analysis of the data leads into a consideration of the anatomy of the viscus in terms of the acceptable theories of the origin of the lesion. It is commonly believed that infection of the gland occurs by passage of organisms through the duct opening in the intestines, especially when there is swelling of the mucosa of both. For the human being the idea is current that infection or obstruction of the common bile duct may spread to the pancreatic duct, and that mechanical or inflammatory obstruction of the papilla of Vater may permit the bile to pass up the pancreatic duct. This theory is based upon certain observations, notably those of Opie, in cases, where a gall stone obstructed the ampulla, bile entered the pancreas and acute pancreatitis arose, partly by the activating action of the bile upon the pancreatic juice and partly by bacteria introduced at the same time. This method of origin is perhaps accepted in most quarters, but there are some who believe that infection of the gland may occur by the infiltration of lymphatics around the pancreas by disease of adjacent parts—gall-bladder, stomach or lymph nodes. Quotation has already been given to reference literature, and I shall not go further into theory except in pointing out how our material may help to answer the question.

In the first place it seems perfectly obvious that infection might in any animal travel from the intestine to the pancreas via its ducts, the main question to be settled being the relative importance of the infection via the bile duct. Let us now see if the variations in anatomy will cast any light upon the matter.

Among the 1860 mammals, there are as far as I can determine 1275 which have one pancreatic duct opening in conjunction with the bile duct, 585 in which the former has an intestinal opening independent of the latter. Among this 1275 there are nineteen cases of pancreatitis, while among the 585 there are eight cases, or as 14.9 to 13.6. All Aves have separate biliary and pancreatic ducts and relatively little pancreatitis, although frequently suffering with its most common accompaniment, namely duodenitis. There is therefore some evidence that more pancreatitis occurs when there is a physical proximity or combination of bile and pancreatic ducts.

Active infections of the biliary system in relation to pancreatitis are, however, not as conspicuous as might be 256expected. In the mammals twelve of the twenty-seven cases showed cholecystitis or cholangitis; in every instance the form of pancreatitis was acute. Among the eleven avian cases four showed inflammation of the biliary channels, but not of the bladder. Hepatic cirrhosis was observed four times. In a thrush and a skunk obvious infectious cirrhosis existed, and in both a necrotizing pancreatitis was found. A badger suffered with atrophic cirrhosis of the liver and a chronic pancreatitis with acute exacerbation. A deer showed marked perilobular fibrosis with a recent hemorrhagic pancreatitis probably due to duodenal torsion. Nothing very distinctive is to be found in these cases, but they merely make the total of involvements of the liver and its adnexa up to twenty. It is to be emphasized that pancreatitis was not associated with lithiasis in ducts or bladder as described on page 240. Peripheral cholecystitis and plastic inflammations about the pylorus and lesser omentum are exceedingly rare in wild animals, while they are not common in human surgical practice. They did not occur at all in mammals in this series, the only external inflammations being in lymph nodes in cases of frank infectious character. There were distinct adhesions between liver, duodenum and pancreas in two birds, one with acute, the other with chronic pancreatitis.

In so far as the kind of pancreatitis is concerned mammals had twenty-two acute and six chronic forms, one animal having the former implanted on the latter, while birds had five acute and six chronic. The preponderance of acute over chronic lesions in mammals again recalls the association of the biliary and pancreatic ducts, but if one expect that such a relation establishes acute inflammation, the relatively high figures for Rodentia and Ungulata, with a single duct removed from the bile duct conflict with the data for orders having two ducts such as the Carnivora. Every case in the former orders was of acute nature; only two had any hepatic disease, four 257had lymph gland hyperplasia in the pancreatic region, and seven had acute enteritis. The preponderance of acute over the chronic cases in mammals and the nearly equal number in birds is, however, apparent.

The collateral pathology with the most definite relationship to pancreatitis is enteritis and one may say that the former occurs in proportion to the incidence of the latter. Acute forms, twenty-seven, were associated with acute enteritis nineteen times. Chronic enteritis was found with chronic pancreatitis in six of eleven cases.

There is a rough relationship between the type of pancreas and the nature of the lesions. The organ may be divided for this purpose into the compact organ firmly held in place by attachments to the lesser omentum, spleen and duodenum, and the velamentous organ which spreads a considerable distance along the duodenum and sends out digitations into the mesentery and thin processes toward the spleen. The first type is seen in primates and carnivores and birds, while the second is characteristic of rodents, ungulates and marsupials. The compact variety showed all but one of the chronic cases while the loose organ was affected by the acute pancreatitis in twelve of thirteen cases.

The microanatomy of the cases may throw a little light upon our subject. I was able to see the duct in one case of acute pancreatitis (bear). It showed a simple catarrhal inflammation with a very moderate circumferential round cell increase. The destruction of glandular areas by edema, hemorrhage and necrosis offers nothing of importance except in a few birds. In these the necrosis is more definite about cross sections of ducts, and the islands of Langerhans are frequently spared until necrosis is locally complete. In a case of chronic pancreatitis in a bird, a cross section of pancreatic duct was found in the intestinal wall; a chronic catarrhal and infiltrative enteritis existed in this specimen. A very definite mantle of round cells was found about the duct while the 258mucosa showed no change, although the lumen seemed large. Interlobular fibrosis was the rule, only one case of intra-acinar pancreatitis being encountered; this specimen, a bird, showed great distortion of the acini and of the islets.

The study of comparative pathology of pancreatitis does not settle its etiology, but some very suggestive facts may be learned. The association of hepatic and biliary disease and of enteritis in the causation of pancreatitis seems amply confirmed, and the latter factor is in our series numerically the greater. It is suggestively shown that inflammations of the pancreas occur more frequently in the zoological class in which the ducts of the organ and of the liver empty into the duodenum together or in close association. Moreover, infections of the liver and adnexa are very important in the mammals, more so than birds in which enteritis, notably chronic in type, usually accompanied the involvement of the pancreas. This is consistent with the incidence of bile tract disease as already discussed under that subject, and it is interesting to note that the mammals showing the greatest number of cases of choledochitis and cholangitis also show the high case incidence of pancreatitis. The birds that have bile tract disease have little pancreatic disease. These facts when considered in connection with the free biliary supply of the avian duodenum, the disassociation of the ducts of the two glands and the close apposition of the pancreas to the duodenal wall, suggest strongly that direct infection of the pancreas can occur from the intestinal wall along the walls of the ducts perhaps via the lymphatics. This is supported by the observation of at least one case in which there was a definite inflammation under the adventitia of the pancreatic duct, its mucosa being normal. The study also suggests that acute pancreatitis is more often associated with acute lesions in the intestines and with hepatic or gall-bladder disease, and that chronic pancreatitis seems more often the result of chronic or repeated intestinal inflammation. Peripheral inflammation such as occurs in gastric or duodenal ulcers, has not been encountered in a distinct character so that its value cannot be estimated.

Fig. 20.—ADENOMA OF PANCREATIC DUCTS. CORSAC FOX (CANIS CORSAC).

259Cystic change in the pancreas has been observed a few times, but never a large visceral collection or the so-called extra-pancreatic cysts of the omentum. One acinus cyst was seen in a drake, one congenital cyst in a lark, and multiple ductal cysts were seen in a baboon and a duck. The parenchyma in all cases seemed entirely capable of functionating.

Tumors of the pancreas have been three in number, two being of academic interest only. One of these concerned an apparent adenoma of the ducts within the organ, discovered microscopically in the sections from a Corsac Fox (Canis corsac). This is the only specimen we have had, and I can find no description of the normal microanatomy of this species, so that with a knowledge that certain carnivores have convoluted ducts, the determination is made tentatively; it corresponds microscopically to a ductal adenoma. The pancreas of a raccoon (Procyon lotor) showed a true adenoma of glandular acini as two separate but closely applied firm nodules surrounded by a capsule, and with distorted acini as seen under magnification. The most important tumor was found in an Indian Paradoxure (Paradoxurus niger), an adenocarcinoma involving the head of the organ, enlarging it to twice its normal size; there were no metastases. The animal suffered also with an infective hepatic cirrhosis of recent origin, chronic nephritis of the arteriosclerotic type, chronic fibroid splenitis. No obstruction to the biliary channels existed.

SECTION VII THE ALIMENTARY TRACT, PART 4. THE PERITONEUM

This visceral envelope is principally important because of the fatal character of its acute inflammations. In man peritonitis of acute origin and type is commonly secondary to a focus of progressive inflammation in some abdominal organ and usually speaks for the virulence of the primary disease and for the low resistance of the serous membrane. Because of this vulnerability, greater foresight is attempted to prevent the extension of acute intra-abdominal inflammations and under operative conditions punctilious care is used to avoid contamination of the general peritoneal cavity. Involvement of the peritoneum in septicemic states is relatively uncommon in man, but seemingly more frequent in the lower mammal. This surface seems more resistant to infection at operation in the lower animals since post-operative peritonitis after castration and experimental procedure is certainly infrequent; our data will permit no percentage figures of vulnerability under such conditions. Judging, however, from the number of times at which the diagnosis of acute peritonitis has been made, the lower animal has a decidedly low percentage resistance although its pathological states are primary or secondary to conditions unusual in man. Among the 5365 autopsies acute peritonitis appears in the diagnoses 137 times or 2.4 per cent.; mammals, 57 or 3 per cent.; birds, 80 or 2.3 per cent.

The exact causes are usually obvious, practically always so in human medicine, but a number of cases escape adequate explanation. From a practical standpoint two origins are important to zoological collections, 261trauma and intestinal perforations by sharp objects. Ungulata frequently suffer abdominal injuries in fighting, as do rodents. Peritonitis sometimes supervenes even in the absence of penetrating wounds, probably by reason of damage to the intestine whereby its permeability is increased. Pointed objects are frequently swallowed by animals and perforation occurs. The danger of feeding split bone to carnivores is well known; some years ago we lost two tigers and a lion in this manner.

Ileus, in one of the several forms, has been an occasional cause of peritonitis in primates and ungulates. The extension of purulent inflammation, abscesses and the like is easy to understand, but we have seen several cases of apparent extension from enteritis without perforation. The reason for this is probably in the kind of enteritis. Monkeys with amœbiasis and gallinaceous birds with enterohepatitis have supplied most of the cases, these infestations of the gut wall being deep and spreading so that a chance is afforded to penetrate the serosa along blood and lymph vessels. One case in a deer seemed to originate from a simple catarrhal colitis; trichocephalus in the colon may have helped. Parasites are not very potent in causing an acute peritonitis, but aggravate the action of other agents. Septicemic states are at the bottom of 24 per cent. of our cases of peritonitis. This is particularly true of birds, it being recognized that their acute general infections frequently have such an effect, but the primates and carnivores also have a vulnerable peritoneum when septicemia exists. The principal outstanding visceral lesions in the mammalian cases is pneumonia; in birds it is cholera and plague. The rupture of eggs in birds lays the foundation of a peritonitis, while bacteria from the oviduct or cloaca complete the process. Chronic peritonitis is not common. It is usually due to parasites or to tuberculosis. There 262has been observed, however, no complete general involvement of the peritoneal cavity including the liver and spleen, sometimes called “sugar-icing,” and believed to be tuberculous in origin. The only tumor found in very close association with the peritoneum occurred in a Chapman’s Zebra (Equus burchelli chapmani) in which animal a fibromyoma seemed to spring from a loop of intestine and grow away from the gut wall. It was undergoing myxoid change.

SECTION VIII THE URINARY TRACT — The Kidney. — Kidney Weights. — Absence of Abnormalities. — Hypertrophy. — Infiltrations. — Degenerations. — Hemorrhages. — Nephritis. — Ascending Nephritis. — Histology of Nephritis. — General Effects of Nephritis. — Calculi. — Tumors.

The kidneys, ureters, bladder and urethra remain comparable in all mammals excepting the monotremes where there is no urinary passage through genital openings, the urine being ejected through the vesicoanal pouch, a sort of cloaca. In the bird the first two parts remain as in mammals while the ureters terminate in a hernia-like pouch of the rear wall of the cloaca. It would seem from this arrangement that ureteral transmission of infection from the anal area to the kidneys would be facilitated in the lowest mammals and in the Aves. Variations in size, shape and position exist to a minor extent in the higher orders but in all forms, the system remains a post-peritoneal structure.

Differences in construction are to be seen for example, in the single pyramidal kidneys of marsupials and certain rodents, in the lobulated organ of bears, cattle and seals, in the twisted viscus of horses, but these gross appearances do not destroy the uniform scheme upon which the functionating unit is built. The single-lobed kidney discharges all its collecting tubules into one calyx while the multiple pyramids of the lobulated organ are fitted with individual calices which in turn empty into the pelvis proper; this is true whether the lobulations are retained, as in the bear, or are smoothed out in the course of development as in man. The secretory tubule remains in essentially the same form in all kidneys; the modern idea of its anatomy may be found in the work of Huber^[32].

The most decided example of the lobulated kidney is to be found in the class Aves, wherein the organ consists 264of two or three large lobes lying in concavities of the sacrum, each lobe being made up of tiny lobules. The latter appear to the unaided eye as fairly distinct divisions whether viewed on the exterior or by cross section. There is a cortex and a medulla to each, the separation being clear in a large specimen, vague in a small one. These lobulations are quite well observed when the kidney is full of urates, a common finding in birds. Magnification of the avian kidney reveals an apparently simpler tubular arrangement than is found for mammals^[33][34], yet the relation of vascular plexuses and secreting tubules remains similar.

From the standpoint of comparative pathology attention can be drawn to the glomerulus, to the interstitial tissue, and to the character of the epithelium. The tuft of intricately wound capillaries called the glomerulus has always been viewed as the part of the secretory unit chiefly concerned in urine production whether one accept the older idea that it excretes only fluid or the modern belief of many observers that all parts of the urine go out through it. In the mammal the tuft is closely wound, is surrounded by a distinct space and a limiting membrane of appreciable width called Bowman’s capsule; all this so-called Malpighian body has a breadth varying from 120 to 300 micra. There is however great variation in the size of this body when seen in the peripheral and deeper zones of the same organ, amounting at times to seventy per cent. of the diameter. The capillary congeries forming the avian tuft is by no means so delicate and one can see individual capillaries with more ease. It may be impossible to discover a space between the tuft and its exceedingly delicate capsule, the latter being usually applied closely to the vascular corpuscle. The whole breadth varies from 70 to 140 micra with an average 265of 110. There is more uniformity in size than in the mammalian organ.

Supporting tissues between the tubules seem less definitely nuclear in the bird than in the mammal, at least in so far as connective tissue is concerned, there being in the former only a few groups of mononuclears to be seen in the cortex. Perivascular tissues are reasonably rich. The epithelium of proximal and distal tubules is not easily fixed by our customary laboratory techniques, the best results being obtained by Zenker’s fluid. As seen in a routine specimen of a normal organ it is vacuolated or very palely stained. The individual cells stand out clearly and many present a pointed end to the tubular lumen.

According to the work of Mangan^[35] and of Alezais^[36], the bird has an average kidney-to-body weight of 6.9 grams per kilo while man has a ratio of 4.3 grams, dog 5.9 grams and guinea-pig 8.5 grams. The first author would show that the fish-eating birds have the heaviest and vegetarian birds the lightest organ. Our own figures are limited to the weights of apparently normal organs in thirty-one mammals and five birds; they are as follows:

This to be sure is not a very exhaustive list but is the result of our routine observations and subject to all limitations 266of such work. Grossly diseased organs are naturally excluded. More avian weights are not available because of the difficulty of removing the organ from its bed, in a manner assuring us of completeness. I am inclined to view our mammalian records as fairly representative. Figures to be found in text-books of human and veterinary anatomy correspond to those given by the authors just quoted and in our own list. The values for rodents, hyraces, edentates and monotremes may be modified by more figures.

There is however one point which does not appear in the list. Small animals have relatively larger kidneys than large animals. This is perhaps most strikingly illustrated among the ungulates which have the lowest value quoted. A small deer had a kidney-to-body index of 5.9 grams per kilo while a camel had only 2.8. Judging by the work of Magnan the avian kidney should be larger than the mammalian, a conclusion with which I am inclined to coincide, even though the weights cited do not bear this out.

In so far as the function and chemistry of the kidney and its excretion are concerned this study can supply little. The general metabolism is known for most animals, it being dependent upon diet and gastrointestinal discharge of excrement. What lessons can be learned will be discussed by Dr. Corson-White in the section on diet. Our observations upon the ability of the kidney to excrete normal urine are limited to the examination of vesical contents at death or of the occasional specimen obtained in cages in the quarantine room. Renal disease was formerly considered of little or no importance in veterinary medicine or at least was studied only as a specific separate and occasional occurrence. Kitt^[37] systematized the knowledge of the subject at the time he wrote but it remained for Hutyra and Marek in their text-book to emphasize its general importance and to 267clarify diagnostic measures. Breindl^[38] pointed out that nephritis occurs more often in acute general diseases, notably the specific infections, than was customarily thought, thus placing the subject for the lower animal where it is in human medicine.

Renal disease is quite common among wild animals albeit there are certain orders in which the lesions are less conspicuous. Clinical diagnoses of nephritis, and this is the only diagnosis attempted, have been made on monkeys by examination of urine which shows the same characters as in the human disease. In ungulates more attention is to be placed upon the cellular contents of the urine since renal epithelium is apparently shed more readily and casts less often formed. Signs and symptoms of renal disease are limited to edema and uremia; cases of the latter are rare enough to discuss separately at the proper place.

Abnormalities of size, shape and position of the kidney are frequently reported in literature of veterinary medicine and aplasia has been described. Our material has failed to present cases of horse-shoe kidney well known to occur in horses, cows, sheep and dogs. Wandering kidneys are also known but have not been seen in our wild animals. Shall these abnormalities be considered as due to degenerative changes in cross bred animals or as the result of the strain of domestication? To such a speculative question our material affords no answer.

That the kidney has the power of hypertrophy in a compensatory manner is illustrated by two cases. A Japanese Macaque (Macacus fuscatus) ♂ apparently had suffered with a unilateral nephritis which had gone into a contracted stage. At all events much functionating tissue 268was gone, the organ irregular and small, being half or less of the size of the other organ which was larger than is considered normal for the species. Histologically the large organ was practically normal. A common opossum (Didelphys virginiana) suffered with a complete suppurative nephritis of the right side which completely destroyed the organ; the origin of this is not clear as no ascending disease could be determined and no certain acute infection had existed; decomposition precluded satisfactory bacteriology. The left kidney was nearly twice its normal size and involved in an early diffuse nephritis, with miliary abscesses, in which the glomeruli did not participate. There were in these sections evidences of regeneration, swollen reduplicated epithelial coverings presenting a picture similar to those seen in so-called chronic nephritis secondary to interstitial change.

Pathological infiltrations of the renal structures are exceedingly uncommon. Early in our experience we were often perplexed at the appearance of certain organs, notably in carnivores and marsupials to which we were inclined to apply the term fat infiltration. However the absence of reasons for considering this picture pathological seemed sufficient cause to ignore the finding, and later Pfeiffer^[39] called attention to the apparent inability of these kidneys to emulsify fat or at least to combine it in an invisible form, an ability possessed by the herbivorous organ. A monkey and a passerine bird only showed sufficient fat visible in the renal epithelium to warrant a denomination of fatty infiltration; these were both obese specimens. Amyloid infiltration occurred in four mammals and six birds, being a sequel of its usual causes, tuberculosis, chronic suppuration and osseous system disease. It is perhaps well to emphasize the fact that every organ the seat of amyloid deposit need not be 269enlarged. This teaching is common but I have seen human cases without enlargement and only two of the ten cases in these animals are noted as bulkier than normal.

Degenerations represent the reaction of the kidney to toxic or infectious agents and might be considered as indicating the vulnerability of the organ. Their incidence does not coincide with that of nephritis as we shall see later. Any discussion of degenerative phenomena, and especially in the kidney, should be limited by a definition of what they are believed to be and their separation from inflammations. Degenerations are swellings, granularities, vacuolizations or infiltrations of tubular epithelium, changes which destroy the outline and internal structure, perhaps including the nucleus. No changes of the glomerular tuft or interstitial tissue are necessary for this conception since when these occur the picture becomes that of nephritis. In border-line cases it is safer to include the case under the latter heading since then the physiology is apt to be disturbed, albumen and casts appearing in the urine. Degenerations appear in various pathological states—toxemia, infection, prolonged congestion and others. The first named cause seems to be the most important in our records and the seat of the toxine production seems to be the intestine. Enteritis stands very high in the list of accompanying factors, especially in Carnivora, Primates and in Aves. Perhaps the most instructive cases are to be found in the Ungulata with toxic duodenitis. The kidney in these animals is deep red or purple, with a spanned capsule. The section surface bulges slightly, is of an opaque, dull purple color and shows a congested zone between cortex and medulla. Tubular epithelium may be found, under the microscope, sufficiently swollen to fill the lumina, in places being like ground glass, in others distinctly vacuolated. It cannot 270be stated absolutely which part of the tubule is usually affected; it seems more often the distal convoluted portions than other subdivisions. Glomeruli may be full of blood but there is no increase in cells nor any material in the capsular space. The urine is dark and may or may not show albumen. The kidney of kangaroos with streptothricosis is similar to the picture just given.

Mammals have shown a percentage incidence of renal degenerations of 4.8 per cent. while Aves show only 3. per cent. In order of incidence the carnivores head the list followed by Lemures, Accipitres, Rodentia, Primates and Marsupialia; the remaining groups show but a few cases. A form of degeneration is sometimes seen in the avian kidney the seat of excess urate collections, especially when these are arranged as so-called uratic infarcts. This last term has been applied to the streaking and mottling of human kidneys by the accumulations of these salts in a manner believed by some to be related to the formation of uratic calculi. The epithelium of such a kidney may show granularity and collections of acids and salts have been found in the lumina. In the bird on the other hand one frequently sees masses of urates in one lobule, or a part thereof, arranged to simulate closely the common infarct shape. Secretory cells in the affected area are hydropic, with absent or dislocated nucleus, or again they present a densely basic staining protoplasm. This form of kidney is well seen in what has been called here an uratic serositis, a coating of all somatic free membranes with a thin, white, granular film. We have tried with many techniques to preserve one of these cases but the deposit either dissolves or the whole specimen becomes opaque. Although the term infarct is applied to these lesions, they are of course not infarcts in the customary use of the term. True infarcts are exceedingly uncommon and, with the exception of one case which became infected and suppurated, have been negligible in our material.

Hemorrhages into the kidney are found in acute infections and certain diseases like leucemia; they are of little moment. Perirenal hemorrhage is a somewhat striking and unusual affair. Recently I saw at a human autopsy of a young subject a subcapsular hemorrhage from the renal substance probably due to vascular rupture in an acute nephritis; there was no history of injury. There have been three cases of subcapsular hemorrhage in our records and as two of them represented the immediate cause of death, are interesting enough to record. An armadillo suffered an acute diffuse nephritis with much congestion but not enough to call it hemorrhagic. There was a large hemorrhage around the left organ, probably from a vessel near the hilum, sufficient to compress the kidney and cause it to atrophy. A lion presented an acute vegetative endocarditis with all its usual complications. The right renal capsule was distended with recent clot to a size which reached to the pelvic brim. Presumably an embolism caused thrombosis, ulceration and rupture of some middle size vessel. A dormouse suffering with an acute general infection probably emanating from the intestine, had several small recent clots separating the kidney from its capsule.

Nephritis, whether one begin its conception with the clinicopathological picture originally given by Bright, with the purely pathological classification of Weigert and Virchow or the modern tendency to subordinate all physical changes to clinical phenomena, is nevertheless a process of degeneration and inflammation affecting the secreting and supporting structures of the kidney and leading to some degree of impaired function. The disease is bilateral in so nearly every case that for practical purposes unilateral cases may be ignored. This implies that for some reason the renal tissues are generally susceptible 272to etiological agents so that when one side is affected its fellow seems always to participate or to follow. It seems desirable in studying nephritis to evaluate fully the mutual relations of functionating and supporting tissues and of the various sections of the first named. It is taught in many places that inflammations of one or another of these parts may occur independently, as for example a tubular nephritis, a glomerulonephritis and an interstitial nephritis. If however one reflect upon the dependence of the tubular function upon the glomerulus and vice versa or upon the effect of inflammatory exudates in the supporting tissues upon the blood supply of the tubule, it becomes evident that only the most trivial or evanescent pathological changes in one can be without effect upon the others. It is difficult to see how, for examples, a glomerulus could remain normal if its associated tubule were destroyed or how if round cell infiltration or pus surround a capsule for any length of time, this structure could fail to be doomed. All this is by way of directing attention to the progress of physical damage in a kidney which has received injury sufficient to cause nephritis, but of course it does not explain the cause.

In classification of nephritis different commentators have employed different standards according as they viewed the acuteness or chronicity of the process, or as the principal functionating structures, glomerulus, tubular epithelium, blood vessels, or supporting connective tissues, presented the most conspicuous changes. To these, clinicians have added phenomena of constitutional complication or of direct renal insufficiency. These latter being unavailable for us, we must fall back upon a classification based upon physical changes and to this end we have always used a slight modification of the Weigert method. This classification offers little in the direction of etiology except that toxins are believed to cause tubular changes, bacteria to produce glomerular lesions 273and vascular deficiencies to lie at the root of chronic interstitial nephritis.

The origin of acute nephritis of chiefly degenerative character seems best explained by reference to some form of toxemia, whereas exudative processes, be they in glomerulus or supporting structures, seem to depend upon the direct action of bacteria. The origin of a chronic nephritis cannot be explained quite so readily. No one has answered with complete satisfaction whether a chronic process always begins with and proceeds from a single attack of acute disease, whether many acute attacks succeed upon one another or whether many small crops of agents successively attack the organ over a long time. Nor has an adequate explanation of the rôle of damaged blood vessels been given. It is reasonably easy in man to discover the existence of nephritis and of a possible cause; this is only true of acute cases in wild animals. Focal infections, those which might be the point of mobilization for bacteria sent to the kidneys, are frequently found in man but with exception of an occasional carious tooth, or a chronic osteitis are to be localized with difficulty in lower animals. In so far as the rôle of a single acute attack in the causation of chronic disease is concerned our material offers nothing, but some collateral or presumptive evidence may be mustered in regard to multiple infections.

Wild animals do not give evidence of repeated attacks of acute disease and indeed it would seem that they more often die of an acute infection than live to have it repeated. Evidences of chronic infection, not focal, are reasonably definite in forty-eight per cent. of the cases of chronic nephritis encountered here. This suggests strongly that in this material protracted infectious states offer opportunities for renal damage of progressive character. Vascular disease has been found twenty-eight times (see also section on arteries), in twenty-six of which the nephritis seemed due to or advanced by the damage to 274the vessels. This means further that only 14.3 per cent. of the chronic forms and 4 per cent. of the total seem closely related to disease of blood vessels.

Nephritis has been found in 12.2 per cent. of our total autopsies. Mammals show an incidence of 20.6 per cent., birds 7.7 per cent. Only the orders upon which more than one hundred autopsies have been held are subjected to separate analysis. Some of the remaining orders give very high figures which may indicate great renal vulnerability but it is deemed unfair to make statements upon them. Carnivorous mammals and birds lead their respective classes, the succeeding order of renal vulnerability being marsupials, ungulates, rodents, Primates, Galli, Striges, anserine birds, parrots, and doves. The leaders of this list, Carnivora and Accipitres, occupy a definite position in the analysis of acute and chronic lesions. Their kidneys show the smallest percentages of acute lesions and the highest percentages of chronic lesions. This would seem to indicate a resistance to acute injuries but susceptibility to prolongated or repeated infections or intoxications. The relation of chronic infection of some sort to chronic renal disease is not as clear as the influence of acute infection to acute nephritis. Taking Carnivora for example with 34.2 per cent. of chronic nephritis we find 22.4 per cent. with evident chronic inflammation while in the 55 per cent. of acute forms 40 per cent. are of acute infectious origin—the relation is as 64 is to 74.

While the relation of infection to nephritis is a consistent and perfectly acceptable one, the frequency of this disease in the carnivorous orders obliges one to think of high protein diet as a favoring factor. Renal disease is common enough in other orders, some strictly herbivorous, and it is fair only to emphasize which are the leaders in incidence. In so far as anatomy or habits are concerned no generalizations seem permissible. There is no relation of nephritis to the size of the kidney as given 275on a previous page, to the length of the alimentary tract, or to the expected longevity.

Toxic nephritis is a term applied when the kidney is the seat of epithelial degeneration, much congestion, perhaps leading to tiny hemorrhages, and definite swelling of the tuft without exudation into the capsular space. It is a severe grade of the degenerations already mentioned and is exemplified by the organ in cases of acute duodenitis of ungulates and in some monkeys dying after tuberculin injection. It seems especially to follow gastrointestinal diseases believed to be due to food intoxications. It seems important in monkeys and wild rodents. No adequate explanation is at hand for the latter.

As has already been stated vascular disease was present in twenty-six cases in a manner suggesting some relation to the cardiorenal complex but the only organ to which the term renal sclerosis of arteriosclerotic origin could be applied is that of an eagle; the autopsy is cited.

Bald Eagle (Haliæetus leucocephalus). ♀ General obliterating endoarteritis. Chronic interstitial nephritis. Passive congestion of liver. Chronic localized myocarditis. Near the apex of the heart the muscle shows a slight opacity. The kidney is enlarged, firm, section surface glistening. Both section and surface show a mottled brown and white appearance, following particularly on section the division into cortices and medullæ. Digestive system apparently normal. Microscopic section of heart muscle from the wall of the ventricle shows well preserved muscle fibres with a slightly unusual degree of pigmentation. Section from valve base shows a definite interfascicular and intrafascicular fibrosis which is co-extensive with a similar thickening of the endo- and pericardium. The new tissue under the latter is edematous. The valve itself is thickened the fibres swollen and hyaline. There is no reduplication of the endothelium. One artery in the muscle is obliterated. This is not associated with any degeneration of the muscle in the section. Section of kidney shows the pale areas noted grossly to be made up of groups of arteries with their extensive coalescing adventitiæ. The changes in the arteries are precisely the same as those seen in the liver but are more extensive. Connective tissue goes out from the arteries into the parenchyma distorting the tubules and enclosing the glomeruli so that the capsule of the latter is much thickened. Epithelium is granular, in some places absent, nearly always low. Section of liver shows general parenchyma practically normal with slight granularity in places and moderate passive congestion. Veins are negative but 276arteries show a general arteritis. The picture varies somewhat in different arteries ranging from a simple thickening of the adventitia to a change involving all three layers. There is hyaline change in the media in many sections. Lumen is in all cases reduced and in some there is active intimal proliferation in excess of what would be expected in connection with the medial change. A few of the arteries have their lumen completely obliterated.