Chapter XXXIV: Section XVIII: The Animal Parasites, Their Incidence and Significance (2)

The adult _Hepaticola hepatica_ of prairie dogs I have not seen in sufficient entirety to compare with the rat species and therefore cannot affirm that the two are identical species. It is presumably like that of the rat, being threadlike and most difficult to separate from the liver substance through which it ramifies. At maturity it dies and disintegrates, leaving the ova distributed more or less in tracts through the liver substance, so that we are limited to a certain period wherein to obtain the mature form. The ova are not passed into the intestine, but remain _in situ_, just as in the case of hydatid disease, and therefore diagnosis cannot be achieved by examination of feces. For the disease to be transmitted the host must die and its carcass be eaten or otherwise so disintegrated that the ova are distributed abroad. Another interesting observation is the long incubation period of the ova. Confirming Bancroft, we found that the ova only became larvated after they had lain in water at least three months.

HOOKWORMS.

These important parasites have been taken from several foxes: Gray Fox (_Canis cinero argenteus_), Arctic Fox (_Canis lagopus_), Swift Fox (_Canis velox_), Red Fox (_Canis vulpes pennsylvanicus_), a Gray Wolf (_Canis mexicanus_), divers members of the Felidæ-Eyra (_Felis eyra_), Jaguarundi (_Felis jaguarundi_), American Wild Cat (_Felis ruffus_), Spotted Wild Cat (_Felis ruffus texensis_), Ocelot (_Felis pardalis_), from two Giraffes (_Giraffa Camelopardalis_, _Giraffa capensis_), a Malayan Tapir (_Tapirus indicus_), and a young California Hair Seal (_Zalophus californianus_). It has been a most serious infestment in American wild cats (_Felis ruffus_ and _Felis ruffus texensis_)—animals which generally also harbor other species of worms. In view of the petechial hemorrhages of the intestines and analogous circumstances in dogs and human beings, it must be conceded that this worm is pathogenic.

At this point it is fitting to note the infestment as it affects hair seals. The parasite concerned, _Uncinaria lucasi_, has long been a scourge among the fur seals (_Otoes alaskanus_) of the Pribiloff Islands. Its punctures are bloodless, being signalized instead by small edematous plaques in the intestinal mucosa, The animal we autopsied was a young California Hair Seal born in the Garden, and is singularly the only hair seal in which we have seen it. The natural habitat of the hair seal is the coast of California which means that the range of _U. lucasi_ may extend farther southward than at first suspected. We have none of the northern variety.

I point out two giraffe cases only because they are unique as to the organ (liver) affected. So far as I know, mature hookworms have never been reported from other organs than the intestines.

From the prophylactic standpoint it will be advisable to have as little moist earth as possible, particularly sandy ground, in and around the enclosures for the above mentioned susceptible animals because it is in such soil that the earlier stages of the life cycle of the parasite are passed.

We have never found any of the human hookworm species in our animals, but it must be recognized that transmission is possible to a certain degree. _Anchylostoma ceylanicum_ Lane[136] was found in man, cats, dogs, and a lion; Leiper[137] reports _A. duodenale_ in a dog, and von Linstow[138] states that the latter parasite also occurs in the chimpanzee.

AMEBIC DYSENTERY IN MONKEYS.—We recently lost six monkeys in a small outbreak of this disease—four black spider monkeys (_Ateles ater_), a Pinche marmoset (_Leontocebus edipus_), and a woolly monkey (_Lagothrix lagotricha_). Except for non-characteristic looseness of stools, there were no symptoms until the usual terminal lethargy set in. Living amebæ were found in feces. At autopsy only the colon was found to be anatomically affected. It was hugely distended, fully an inch in diameter, and there were numerous confluent ulcers of the mucosa covered by a thick slough. The liver showed no abscesses. In the histological sections amebæ were found in the interstices of vital gut tissue just as they are in corresponding human lesions. I have not diagnosed the species yet, but can vouch that it is not _Endameba histolytica_ or _coli_.

FIG. 78.—MICROSCOPIC SECTION OF LIVER OF GIRAFFE, SHOWING SECTIONS OF
UNCINARIA SMITHI IN BILE DUCT AND MARKED FIBROSIS AROUND THE DUCT.
]

FIG. 79.—COLON OF MONKEY DYING WITH AMŒBIC COLITIS. HIGHLY ELEVATED
SLOUGHS COVER THE ULCERS.
]

According to Leidy’s recommendation, grated nutmeg was administered and was followed by an improvement in symptoms. The animals became brighter and the stools firmer, but the amebæ were not eradicated. Emetin hypodermically and by mouth had no obvious effects on the disease or the amebæ. One monkey thus treated with nutmeg recovered, but died the next year of another affection and disclosed the scars of the old ulcers in the colon. Our experience with this disease, however, is not unique. At Washington, D. C.,[139] eight spider monkeys were affected, and sporadic cases come to light from the West Coast[140], Manila, Khartoum and Ceylon. Prowazek’s report concerned a young orang[141]. Liver abscesses in addition to the intestinal lesions were found by three different observers.

As to the transmissibility of monkey amebiasis to man, reporters are divided. Both sides are probably right, in as much as _Endameba histolytica_ was concerned in some cases and non-human species in others. It is an infestment to be feared, and calls for examination of stools from such newly arrived animals as are known to be susceptible (spider and woolly monkeys, orangs).

PARASITES OF MARMOSETS AND SQUIRREL MONKEYS.—I give a special place to this subject because Table 24 shows that these monkeys are so commonly infested and because they are so commonly used as household pets. In this connection the questions arising are, first, whether the infestment is a menace to life, and second, whether it is existent outside the Garden or only acquired here. The following lists set forth the parasitic status as shown at autopsy. The figures indicate how long the animal lived in the Garden:

═════════════════════════════════════════╤═══════════════════════════
Marmosets │ Squirrel Monkeys
─────────────┬───────────────────────────┼─────────────┬─────────────
Infested │ Not infested │ Infested │Not infested
─────────────┼───────────────────────────┼─────────────┼─────────────
1 day│ 6–15 days ( 4 animals)│ 2 days│ 3 months
1 day│ │ │
2 months│ 1 month ( 6 animals)│ 14 days│ 3 months
6 months│ 3–5 months ( 9 animals)│ 26 months│ 5 months
12 months│ 6 months ( 2 animals)│ │ 14 months
12 months│ 7 months ( 2 animals)│ │ 15 months
12 months│ 8 months ( 1 animal)│ │
13 months│ 9 months ( 2 animals)│ │
│ 10 months ( 1 animal)│ │
│ 12 months ( 1 animal)│ │
│ 14 months ( 1 animal)│ │
│ 15 months ( 1 animal)│ │
│ 17 months ( 1 animal)│ │
│ 18 months ( 2 animals)│ │
│ 20 months ( 1 animal)│ │
│ 21 months ( 1 animal)│ │
─────────────┼───────────────────────────┼─────────────┼─────────────
Totals 8 │ 35 animals│ 3 animals│ 5 animals
animals │ │ │
─────────────┴───────────────────────────┴─────────────┴─────────────

Reverting to the questions above raised, the data show that some of the animals were certainly infested on arrival here, and that others probably were; but since these animals were not examined for parasites on arrival in the Garden the duration of infestment remains unknown, and accordingly we are not justified in going farther in our conclusions. In the case of the marmosets, though, if we confine ourselves to the non- parasitized animals, it would appear that the “acclimatization” period is within the first six months. I have attempted to arrive at a conclusion on this basis, but the average lifetime of the four parasitized marmosets which survived this period is the same as that of the sixteen non-parasitized survivors, and we do not know at what time the parasitized ones contracted the disease.

FIG. 80.—ARACHNID (PNEUMONYSSUS FOXI) IN LUNG OF ADULT MONKEY (MACACUS
RHESUS). IT OCCUPIES THE CENTRE OF A CYST WHICH IMMEDIATELY
UNDERLIES THE PLEURA SEEN AT UPPERMOST PART OF THE ILLUSTRATION.
]

CYSTICERCUS TENUICOLLIS.—We have noted this bladder worm in the Aoudad (_Ovis tragelaphus_), Red River Hog (_Potamochœrus porcus_), domesticated Angora Goats and several deer (_Cervus alfredi_, _Capreolus capreolus_, _Mazama mexicana_, _M. hemionus_) located with one exception in the peritoneal cavity or membrane. One of the mule deer (_Mazama hemionus_) exhibited the parasite also in the lung and liver. This parasite is discussed because the very valuable Philippine spotted deer (_Cervus alfredi_) died from a peritonitis secondary to an infected cyst in the lesser omentum, and because the parasitism (_Tænia marginatum_) is contractible from canidæ which are also on exhibition in the Garden. It happens that the spotted deer did not become infested from the dogs, but it is quite probable that the goats did, since they passed many times daily in front of the wolf cages, drawing the children’s carriages over the walks, and were stabled nearby. We have not discovered any of the other tapeworm cysts in deer which might be transmitted to them from the canidæ. Camels which are parked directly opposite them have only exhibited echinococcus cysts, yet we have never found its adult form (_Tænia echinococcus_) or its ova in the canine feces. The danger of fatal disease from _C. tenuicollis_, even though the infestment be present, is remote; but we feel that it is better, if possible, not to exhibit the canidæ adjacent to susceptible animals.

PULMONARY ACARIASIS IN MONKEYS.—We have seen but two instances of this affection in the Philadelphia Garden. The offending parasite in our animals was a new species, _Pneumonyssus foxi_ Weidman[142]. It occurred sparingly in small cysts under the pleura and was certainly benign in our cases. The importance of the infestment consists in part in that these lesions may be mistaken for tubercles.

At the London Gardens[143] acariasis was found in forty-four young rhesuses dying of pneumonia, and the observers ascribed the inflammation to irritation of certain doubly refractile crystals which occurred in the excreta of the mite. There are four other recorded instances of such disease in monkeys, all caused by different species of parasites.

As to pathogenesis of these arachnids, the London experience is most illuminating in that it was young rhesuses that were affected. Our specimens were mature, and nothing was stated to the contrary in the other reported cases from various parts of the world. The parasites are perhaps inhaled from the straw used as bedding, since such vegetable material is a common habitat for mites. If the resultant acute pneumonia is weathered the relics might remain only in the form of the subpleural and parabronchial cysts such as we have seen at the Philadelphia Garden.

I am the more willing to accept the possibility that the simian arachnids can induce an acute pneumonia after studying a very definite case of bronchopneumonia in a prairie dog, which was induced by _Cytoleichus penrosei_ Weidman 1916.[144]

PERIPROVENTRICULAR FILARIDÆ OF BIRDS.—Every year we report a number of cases (up to twenty-three) of these worms, probably several species, coiled under the serosa of the air sacs and most commonly around the proventricle. Tentatively we have recognized two forms, a shorter (an inch or so long) and a longer (three to four inches). The latter is most inextricably coiled, but the former may be teased out. Microfilaria occur in the blood of the latter cases, but not in that of the former. The adults have been observed to penetrate from their position in the air sac serosa into the lumen of the proventricle (goose), to have caused rupture of the inferior cava (bulbul), to be associated with subserous cysts of the intestine (weaver) and with profound anemia (liothrix). The birds affected are mostly small, inexpensive ones, but the infestment is important because of its frequency and deserves study of the means of transmission.

FIG. 81.—ARACHNID (CYTOLEICHUS PENROSEI) IN A BRONCHOPNEUMONIC FOCUS
IN THE LUNG OF A PRAIRIE DOG (CYNOMYS LUDOVICIANUS).
]

FIG. 82.—FILARIAL WORM COILED NEAR PROVENTRICLE OF A FINCH.
]

PHYSALOPTERA IN OPOSSUMS AND BADGERS.—These worms were frequent findings for a period of years and were particularly impressive on account of the large number of parasites present. The stomach often contained scores, more or less securely attached to the mucosa by the head. The worms average an inch or two in length and perhaps an eighth of an inch in thickness. _P. turgida_ is the only species we have identified (three examinations). As to pathogenicity we have not observed that definitely constant lesions are induced by the parasites. In several instances the gastric mucosa has shown the mosaic appearance indicative of chronic gastritis, a condition not necessarily incited by, but certainly aggravated by, these worms; at least significant is the habit of the worm to imbed its head in the gastric mucosa. In one instance the microscope has revealed a most severe fibrosis of the submucosa. The fibrosis was not so much diffuse as it was local or nodular, and in favorable places the ova of physaloptera could be discovered in the centres of the nodules, and thus betrayed the previous presence of the adult worm there. In this individual animal the case against the physaloptera is clinched by direct evidence. In other cases we have circumstantial evidence. Whereas it is not a deeply burrowing parasite, it is still a penetrative one, and this is sufficient to compromise the all important “integrity of the mucosa.” It should therefore be considered pathogenic in all cases, because open to suspicion in several directions—abstraction of tissue juices, irritation by its products or movements and by opening up an avenue for bacterial infection.

TROPIDOCERCA IN BIRDS.—This is a blood-red nematode of the size of a mustard seed to that of a peppercorn which inhabits the depths of the proventricular mucosa. At first sight its spheroidal form suggests that of a fluke, but under the microscope it is found to be a nematode hugely ballooned out by ova, and coiled up into a ball. In spite of its dangerous appearance—being red—it is most likely quite innocuous, for microscopic sections show no sign of inflammation around the worm. Moreover, we know that a Concave Casqued Hornbill (_Dichoceros bicornis_) now on exhibition has harbored the worms, as indicated by ova in the droppings, for eight years and yet seems perfectly well. I have made wax reconstructions of three of the worms and find that the coils are not very intricate and that they assume no regular or constant arrangement.

SYNGAMUS TRACHEALIS.—Our worst experience with this picturesque parasite was in common crows (_Corvus b. brachyrhynchos_). In 1914 and 1915 alone we lost five such birds. Some geese, swans and a pheasant complete the short list of birds affected in addition to the crows. In no case was it a young bird that was affected. Shipley[145] reports this parasite in two grouse at the London Gardens, and Plimmer’s tables show that three deaths were directly charged against them in one year[146].

EXTRA-INTESTINAL TAPEWORMS.—This discovery is worthy of record because it is rare for cestodes to appear anywhere save in the intestines. We have observed three instances where they had backed up into the bile duct—twice in the Cape Hyrax (_Procaria capensis_) and once in a Livingston’s Eland (_Taurotragus oryx livingstonii_). At the London Gardens they were mentioned in the gall-bladder of a wallaby and in Cape Hyraces. Beddard[147] carefully describes four new species of these cestodes from the hyrax.

FIG. 83.—PHYSALOPTERA IN STOMACH OF COMMON OPOSSUM (DIDELPHYS
VIRGINIANA). THIS IS NOT AN EXCEPTIONAL DEGREE OF INVOLVEMENT.
]

FIG. 84.—ONE OF THE FIBROUS NODULES IN THE GASTRIC SUBMUCOSA OF AN
OPOSSUM. AN OVUM OF PHYSALOPTERA IS SEEN PRECISELY IN THE MIDDLE OF
THIS ILLUSTRATION.
]

TABLE 28.
_Occurrence of Blood Parasites._
(Adapted from Plimmer, nine year period)
_Animals examined—12,241 Mammalia—2,924 Aves—6,619 Reptilia—2,698._
══════════════════════════════════╤══════════════════╤════════╤════════
Parasite. │ Host │ No. │ %
│ │Infested│Infested
──────────────────────────────────┼──────────────────┼────────┼────────
1. Hemogregarines │Reptilia │ 316│ 11.8
2. Microfilaria │Mammalia │ 33│ 1.1
│Aves │ 191│ 3.
│Reptilia │ 24│ 1.
3. Hemoproteus │Aves │ 140│ 2.1
4. Trypanosomes │Mammalia │ 1│ 0.003
│Aves │ 28│ 0.4
│Reptilia │ 4│
│Amphibia │ 3│
5. Plasmodia │Mammalia │ 2│
│Aves │ 39│ 0.6
│Reptilia │ 5│
6. Leucocytozoa │Aves │ 16│ 0.2
7. Intestinal organisms[148] │Reptilia │ 16│ 0.5
8. Toxiplasma │Mammalia │ 1│
│Aves │ 1│
│Reptilia │ 1│
9. Spirochæta │Mammalia │ 1│
10. Babesia │Mammalia │ 1│
11. Hæmocystidium │Reptilia │ 1│
──────────────────────────────────┼──────────────────┼────────┼────────
Grand Total │ │ 824│
──────────────────────────────────┴──────────────────┴────────┴────────

SUMMARY OF TABLE 28. ═══════════════════════════════════╤═══════════╤═══════════╤═══════════ │Parasitized│ Animals │ % │ │ examined │Parasitized ───────────────────────────────────┼───────────┼───────────┼─────────── Mammalia │ 39│ 2,924│ 1.5 Aves │ 415│ 6,619│ 6.5 Reptilia │ 367│ 2,698│ 14.0 ───────────────────────────────────┼───────────┼───────────┼─────────── Total │ 821│ 12,241│ 6.7 ───────────────────────────────────┴───────────┴───────────┴───────────

FILARIASIS IN WILD CATS (_Felis ruffus_).—This parasite was named _Filaria fasciata_ because it coils in the fascia between the muscles— generally those of the thigh and abdomen. The worms are easily detected on skinning the animal and separating thigh and other muscles. Microfilaria were always present in the blood. The grade of pathogenicity is only conjectural.

PERITONEAL FILARIA IN MONKEYS.—Thread worms have been encountered eleven times, largely in Cebidæ. In several instances _F. gracilis_ has been the species identified, always inhabiting the peritoneal cavity, and in one instance also the lung. Microfilaria were always present in the blood. We have never seen lymphangitis or elephantiasis in our filarial cases.

BLOOD PARASITES.—I justify this paragraph on the basis of the usefulness it might have in the clinical direction, for while the taking of blood specimens is not as easy as with man it can still be done with some animals. From time to time we have encountered blood parasites in this Garden, but the large numbers occurring in the experience of special searchers in the London Garden and Plimmer’s particular interest in this direction make their data much the more valuable. In one report of 6,430 animals examined he found 7 per cent. infested with blood parasites of one sort or another. I have constructed the foregoing table (28) from his various reports to show which animal classes were affected by the several blood parasites.

This table (28) brings out that considering them as a whole and without respect to host, just as the animals come day in and day out to the autopsy table, blood parasites will be met in 6.7 per cent. of all cases. They are seen most commonly in the form of hemogregarines of reptiles (2.5 per cent. of all animals and 12 per cent. of all reptiles) while microfilaria run a close second, being found in 2 per cent. of all animals but much more commonly in birds. Hemoproteus of birds while ranking third, should be emphasized on account of its acknowledged blood-destructive properties. The remaining infestations were too infrequent to be useful statistically.

Turning to individual groups of blood parasites, microfilariæ of birds deserve special comment. They occurred four times more often in birds than in other animals, or, put in another way, one out of every twenty- two birds was affected, and only one out of every ninety other animals. The high figure for birds is significant in relation to what we have already said about periproventricular filaridæ in our Garden, indicating that the same infestment probably also exists in London.

FIG. 85.—ADAPTATION FROM RECONSTRUCTION OF TROPIDOCERCA CONTORTA. THE
WORM LAY IN THE WALL OF THE PROVENTRICLE OF A LOUISIANA HERON (ARDEA
TRICOLOR RUFICOLLIS).
]

FIG. 86.—CESTODES (THREE) PROJECTING FROM THE SEVERED END OF THE BILE
DUCT OF A CAPE HYRAX (PROCARIA CAPENSIS).
]

A point brought out by Plimmer is to the effect that, of the several blood parasites, the microfilariæ were the least harmful, and that of these the adult forms were the only ones to produce symptoms; yet in one place[149] he records microfilaria as plugging the cerebral capillaries of birds. This is a very important lesion if permanent, and especially so when affecting cerebral capillaries as do the organisms and pigment of malaria. The adult forms were found in one-fourth of the cases where microfilaria were demonstrated.

As to the pathogenicity of these blood parasites in general, it will be unsafe to arrive at a definite conclusion, recalling the pitfalls that I have already outlined in discussing pathogenicity of parasites in general. Keeping in mind the wonderful adaptability on occasion of animals to unfavorable circumstances we must hesitate to declare unqualifiedly the importance of even blood parasites as morbid agents. Where the parasite is known to destroy the blood cells of birds and mammals it is otherwise, but even here experimental work would be necessary to settle the question. The element of “racial” immunity and of phylogeny is the fly in the ointment of our deductions.

TRANSMISSION OF ANIMAL PARASITISM FROM WILD ANIMALS TO MAN.

Examples of direct transmission will be only occasional, due to the relatively infrequent contacts between the two hosts. Pets threaten the most. Several such examples have been touched upon in the preceding pages and it but remains to gather them into one place. There is one concrete instance in the form of clear cut simian scabies being transmitted to a keeper in this Garden[150] and a similar lot fell to the keeper of a wombat at the Paris Garden[151] as well as to the taxidermist who preserved its skin. We know that the skin and feathers of our parrots and pigeons harbor mites[152] (plumicoles of Megnin) and, recalling the occasional cases of poultrymen’s itch, a transient affection might be conceded from pet parrots and other birds. Pediculi are not as numerous on monkeys as popularly supposed—we see very few at the autopsy table. We have seen _Trichinella spiralis_ in the polar bear (_Ursus maritimus_)—an animal whose flesh is edible. The hydatid cysts in the camel appear unimportant, but in the livers of deer it is otherwise. Neither of these infestments is dangerous if the meat is sufficiently cooked before eating.

Hookworm disease points thus far only to _Anchylostoma duodenale_ in the chimpanzee and _Uncinaria ceylanicum_ in the lion and tiger. Both serve as reservoirs of the disease, the ova being discharged by way of the feces. Similarly the _Strongyloides intestinalis_ infestment which we have seen in the orang might be transferred to man. Indirectly, Europeans traveling in Africa have made the crucial test that certain ungulates and other wild animals of Africa are the reservoirs of _Trypanosoma gambiense_, the parasite of the well known African sleeping sickness; for this example the blood stream of the beast is the reservoir and a biting insect the means of transmission.

The above examples are cited to emphasize the possibility that parasites of wild animals may have a pathogenic significance for man. They do not exhaust the subject. Many more instances might be cited but the foregoing bring out the important ones which have come to our attention.

TREATMENT.

The recognition of the existence of parasites during the life of an animal, especially those of the skin and intestinal tract whose discovery is easiest, suggests that some means of combating them should be employed. But we are by now quite satisfied that medicinal and disinfective therapeutic procedures, while they have their field of usefulness, are much less to be depended upon for the protection of exhibits than are preventive measures of general hygienic nature. Under the latter heading come the prompt removal of excreta, frequent changes of drinking water, routine examinations of feces of certain varieties, autopsy examinations and incineration of autopsy remains—all of which are part of the requirements of common cleanliness and general disease prevention. I wish to amplify the matter of disposal of feces and general cage-police. Our ideas as to what constitutes thoroughness in this work have changed considerably since Fulleborn’s recent demonstration that ascarid ova[153] could live in formaldehyde for four or five years, and the older one of Galli-Valerio[154] that those of _Hepaticola hepatica_ lived one month in 2 per cent. formaldehyde solution. Evidently the same substances which disinfect do not invariably disinfest; and if the occasion should arise for the most exacting control in this respect, a special investigation of the susceptibility of the individual ova in question would have to be undertaken.

In addition to these general measures we have put up certain special safeguards against parasites. Thus, each specimen of the large Carnivora (lions, tigers, leopards, etc.), has received routinely a dose of santonin every month over a period of several years. We have no figures on which to base comparison with previous periods, but an examination of feces of all the inmates of the Carnivora house in 1916[155] showed that less than one-third of the animals were infested, and of these all save the jaguars showed either small numbers of ova in the feces or relatively non-pathogenic forms. The jaguars had been badly infested for many years with dibothriocephalus. Prior to this examination we had been under the impression that nearly every one of the felidæ ordinarily was infested and if this impression was well founded, due credit must be given, in company with general hygienic precautions, to the routine santonin dosages. It goes without saying that where animals are detected at autopsy with unequivocal transmissible and dangerous parasites (coccidia, amebæ, etc.), the contacts are isolated, examined and if necessary treated for the affection or even sacrificed.

To continue the preventive measures, it would be most desirable to examine at least the blood and feces of all newly arrived animals, but at present this is not practicable on account of the labor involved in the laboratory and in collecting the material, and because all animals do not stand the restraint involved when blood specimens are being taken. At present we are limiting special examinations to the droppings of newly arrived parrots and toucans for _Spiroptera incerta_ and to the feces of certain monkeys for amebæ.

Further preventive measures will depend on the nature of individual infestments as they crop up. Food inspection, screening, sulphur dips, etc., are but a few examples of what might be found necessary hygienically after investigating or establishing the life cycle of our numerous parasitic groups. However we cannot forbear to emphasize again the value of the blast lamp and of paint in the hygiene of animal enclosures—means we believe to be much more potent and quite as practicable as chemical disinfectants.

FIG. 87.—TRICHINELLA SPIRALIS IN MUSCLES OF POLAR BEAR (URSUS
MARITIMUS). THIS WAS AN OLD INFESTMENT, AS INDICATED BY THE THICK
AND HYALOID CHARACTER OF THE CAPSULE.
]

Turning now to the active curative side of the subject, what medical means we have against parasites appertain for the most part to the intestinal ones. The treatment of tapeworms is very hazy and unsatisfactory—areca nut is perhaps more useful in animals than any one other drug. For round worms santonin is most to be depended on although turpentine is useful against the round worm of the Equidæ. The dosage of santonin per month has been—for large bears, ten grains; for lions, tigers, large pumas, six grains; for jaguars, leopards, hyenas, four grains; for wild cats, etc., two grains. The dose of areca nut recommended for Carnivora is two grains per pound of body weight. Since ungulates do not stand areca nut well, iron sulphate may be used. For animals the size of a horse the dosage is two drams, and to this one or two grains of arsenic trioxide may be added. On the basis of very carefully controlled experiments on dogs, Hall recommends carbon tetrachloride for hookworms in these animals—0.3 mils per kilo of body weight, without purging. Its efficacy has been confirmed lately but we have not had the occasion to test it.

From time to time we have broached other lines of medication against worms which may be worth while relating if for nothing more than to illustrate the uncertain ways of our vermifuges when applied to wild animals.

I can speak first of thymol as employed on parrots parasitized by _Spiroptera incerta_. The first thing that impressed us was the large dosage which birds could endure. The lethal dose for pigeons was four grains, suspended in mucilage of acacia. After we had established that certain parrots withstood fourteen grains in mucilage, we administered on one occasion twelve grains and on another sixteen grains, suspended in glycerin. The drug is reputed to be absorbed when exhibited in the latter vehicle and we hoped to get a certain anthelmintic effect on the parasites from the blood side as well as from the lumen of the gut. The bird itself, a very heavily infested cockatoo, showed no ill effects and passed two dead female spiroptera and enormous numbers of ova. But thereafter it passed even greater numbers of ova than before (we estimated 182,000 per day for this bird over a five day period and 288,000 on a single subsequent day), and was obviously unimproved by the treatment. The explanation of failure was clear, for the worms can retire into the protecting mucus or mucous membrane lining the proventricle until the thymol has passed by, and even though paralysed may not be flushed out. In a later test on a toucan which died twenty minutes after thymol administration we found at the autopsy that worms deeply imbedded in the proventricle were translucent and motionless from the effects of the thymol-glycerin mixture, _i.e._, saturated with the medicament and apparently dead. Twenty minutes later they were placed in normal salt solution in the incubator, and next morning were found actively motile. Thymol evidently does not kill—it only stupefies, and in the absence of means for flushing the parasites out, as we do in human hookworm cases, this class of vermifuge will have to be abandoned in work against this parasite.

Not with any serious hope of success, but feeling that arsenic was the most promising drug available for parenteral use, we tried atoxyl hypodermically and arsphenamine intravenously but without success. The only positive results were to emphasize the tolerance of some lower animals to arsenic. Thus in preliminary work pigeons received sixty drops of Fowler’s solution by mouth without embarrassment, but five minims killed a pigeon when administered hypodermically. The organic arsenical, arsphenamine, was withstood intravenously by pigeons in six times the proportional human dosage.

One of our drug trials was instructive in that it worked quite a different effect from that in man, besides being most amusing. In earlier diagnostic work on spiroptera we tested the practicability of examining the vomitus for the worms, hoping thereby to get a greater concentration of ova, which would facilitate the microscopic examination. Hypodermic injections of apomorphine (0.1 grain) into an amazon did not induce vomiting from the gizzard as hoped—only a regurgitation from the crop, but it did cause some dizziness and most ludicrous talking and laughter.

To illustrate further the difficulties of animal medication I quote our experience with four red howling monkeys (_Alonatta seniculus_). One of these died of intestinal obstruction from large ascarids—the case which has been already cited. Ova were found in the stools of the remaining three, and one of the monkeys was treated twice with santonin. It died in thirty hours after the second dose—not of santonin poisoning, for none of the clinical symptoms were present, but most likely from absorption of toxic substances originating in the decomposing ascarids which crowded the gut. It profits not to destroy these parasites, then, unless we feel assured that they may thereafter be removed immediately.

If, for the sake of brevity, I were asked to state in a single sentence the practical status of animal parasitic disease in this Zoological Garden I would put it thus: Since there are various animal parasitic diseases continuously present here of which we know, and since fresh ones are from time to time cropping out, and since these are on the whole of economic importance, it behooves us to continue and extend our efforts against an issue extant—somewhat through therapeutic means, but far more through clinical laboratory examinations, careful autopsy searches, and by rigid general hygienic measures such as cage-police, new quarters, isolation, or if necessary, destruction of the exhibit.

INDEX

Abortion, 305

Abscess of liver, 231
of lung, 155

Acariasis, lungs, 647
of monkeys, 647

Actinomycosis, 138, 568
in deer, 368, 568
tapirs, 568
treatment, 570

Adenoma, 474

Adrenal body, 336

Alimentary tract, 166

Amblyopia, 403

Amœbæ, 606, 644
dysentery from, 644

Amyloid, liver, 227
spleen, 128

Anatomy of labor, 290

Anchylostomum, see hookworms

Anemia, 87
primary, 98
secondary, 88

Aneurysms, 65, 80

Animal Parasitism, hygiene, 656
prevention, 656
treatment, 655

Animal Parasites, 614
disappearance of, 627
frequency, 628
of groups, 633
in blood, 652
incidence, 628–636
modes of action, 617
occurrence in wild, 627
transmission animals to man, 653
visceral distribution, 637

Angina pectoris, 49

Aorta, 72
fatty deposits in, 71

Arteries, 66

Arteriosclerosis, 71

Arteritis, 70

Arthritis, 347
gouty, 347, 411

Ascending nephritis, 276

Aspergillosis, 558

Aspergillus, varieties, 558

Ataxia, 375

Atrophy, acute of liver, 228

Autopsy list, 47

Avian spiropteriasis, 172, 640

Bacterial flora, 418

Basal cell carcinoma, 475

Beriberi, 439

Biliary tract, 225
calculi, 238

Birth canal, 287, 296
comparative anatomy, 287 et seq
obstructions to, 306

Blackhead, 206

Bladder, gall, 224, 238, 239
urinary, 286

Blood, diseases of, 83

Blood formation in birds, 98

Blood vessels, 66

Bone marrow, 83, 109, 111

Bones, diseases of, 343
effects of trauma, 343
tumors of, 368

Botryomycosis, 564, 602

Botulism, 604

Brain, 385
tuberculosis of, 378
tumors of, 384
weight of, 385
references to, 387

Breast, 312

Bronchi, 141

Bronchiectasis, 144

Cage palsy, 349

Calculi, biliary, 238
renal, 282

Carcinoma, 476
basal cell, 475

Cataract, 403

Cecum, 211

Cestodes, 637

Cholangitis, 239, 256

Cholecystitis, 239

Choledochitis, 239

Cholelithiasis, 238

Chondroma, 472

Cloaca, 211

Coccidiosis, 606

Cirrhosis of liver, 232

Comparative anatomy of uterus, 287
of pelvis, 297–303

Conjunctivitis, 402

Constipation, 209

Constitutional diseases, 410

Convulsions, 373

Cornea, 403

Coronary arteries, 49

Cowper’s gland, 313

Cretinism, 320, 331

Cysticercus tenuicollis, 647

Cystitis, 286

Cytoleichus penrosei, 647

Deficiency diseases, 438–443

Degenerations of kidney, 269
of liver, 228

Diabetes, 412

Diet, carnivorous, 452
herbivorous, 452
grain, 455
seed, 454
soft, 453
omnivorous, 402
relation to disease, 415
alimentary tract, 417

Dilatation of heart, 54

Diphtheria, 600

Dislocations, 345

Distemper, 599

Diverticula of intestine, 219

Diverticulitis, 219

Dysentery, amœbic in monkeys, 644

Dystocia, 292

Ear, 409

Echinococcus, 647

Emphysema, 161

Encephalomyelitis, 380

Endocarditis, 52

Endometritis, 305

Endothelioma, 165, 474

Enteritis, 177
in Aves, 202, 205
Mammalia, 185

Enterohepatitis, 605

Epithelioma, 475

Esophagus, 169

Exophthalmic goitre, 320, 323, 329

Eye, 402
tuberculosis of, 402

Fallopian tubes, 305

Fat infiltrations of kidney, 268
liver, 226
metabolism, 445

Fibroma, 472

Filaria, fasciata, 651
gracilis in monkeys, 651
in blood, 652
fascia, 651
muscles, 651
wildcats, 651
periproventricular, 648
peritoneum, 651

Food, 415
definition, 415
in relation to alimentary tract, 417

Food, disease, 422
poisoning, 457

Fowl cholera, 598
plague, 598
typhoid, 598

Fractures, 344

Gall stones, 238

Gas-bacillus infection, 602

Gastritis, 204

Gastroenterocolitis in Ungulata, 194
in Marsupialia, 198

Gangrene of lung, 155

Giraffe, hookworm in, 644

Gout, 53, 410

Heart, dilatation of, 54
hypertrophy of, 54
diseases of, 48
effects of, 55
effect of strain, 55–59
weight of, 63
relative vulnerability of, 61

Hemorrhagic septicemia, 598

Hemoglobinuric fever, 603

Hemorrhoids, 218

Hepaticola hepatica, 641

Hepatitis, 228

Hernia, 216

Heterakis in avian ceca, 606

Hookworms, 643, 654
in giraffe, 644

Hypernephroma, 339, 341, 342, 475

Hypertrophic periosteitis, 346

Hyperthyroidism, 320

Hypertrophy of heart, 54
in Aves, 60

Hypothyroidism, 320

Ileus, 213, 261

Infantilism, 433

Infiltrations of kidney, 268
liver, 226

Inorganic salts in diet, 427

Intestinal obstruction, 212
tract, 177
inflammation of, 181
mechanical obstruction of, 212, 617
relation to food, 422

Intestines, diverticula, 219
tumors of, 220

Iridocyclitis, 402

Kangaroo disease, 570
bacteriology, 576, 586
course of attack, 573
pathology, 575
prevention, 572
treatment, 591

Kidney, 263
abscess, 268, 278
calculi, 282
degenerations of, 269
hemorrhages, 271
hypertrophy of, 267
infiltrations of, 268
tumors, 284
weight of, 265

Labor from a comparative standpoint, 290
obstructions to, 306

Laryngitis, 139

Larynx, 138

Leontiasis ossium, 359, 472

Leucemia, 104
in birds, 108
lymphatic, 105
myeloid, 109

Leucocytes, 84–86

Limberneck of ducks, 604

Lipoma, 472

Liver, 222
abscess, 231
acute atrophy, 228
amyloid, 227
cirrhosis, 232
degenerations, 228
fatty changes, 226
infiltration, 226
inflammation, 228
chronic, 232
necrosis in, 230
tumors, 240

Lungs, 146
abscess, 155
congestion, 148
gangrene, 155
infarct, 160
tumors of, 162

Lymphadenitis, 117

Lymphatic leucemia, 105
tissue, 114
hyperplasia of, 115
in pharyngeal wall, 115, 138

Lymph nodes, 114
tuberculosis of, 121
tumors of, 122

Lymphomatosis, 118

Malnutrition, 424

Mammary gland, 312

Marmosets, parasites of, 645

Marrow of bone, 83, 109, 111

Meningitis, 376

Metabolism, carbohydrate, 443
fat, 445
inorganic, 427
protein, 447

Miliary tubercle, avian, 512
bovine, 510
human, 511
monkey, 511

Miscarriage, 305

Molluscum contagiosum, 601

Mönckeberg sclerosis, 74, 76

Monkey’s temperature, 520–528

Moon blindness, 405

Muscles, 370

Mycosis, 137, 558
of esophagus, 168
histology of, 561
hygiene, 563
incidence, 562
of lung, 562
method of action, 560
pharynx, 168, 564
types of, 560

Myelitis, 350, 381

Myeloma, 111

Myocarditis, 52

Myocardium, 49, 50, 65

Myxœdema, 320, 331

Necrosis, liver, 230
spleen, 130

Nematodes, 636

Neoplasms, 462
incidence of, 463, 468
embryonic origin, 471
in captivity, 469
in the wild, 462, 476
metastasis, 471
visceral origin, 477

Nephritis, 271
ascending, 276
effects of, 280
histology of, 279
toxic, 275

Nervous system, 372

Nocardia macropodidarum, 585

Nocardiosis, 570

Obesity, 446

Ophthalmia, periodic, 405

Osteitis, 346

Osteitis deformans, 359, 431

Osteoma, 368

Osteomalacia, 349

Ovary, cysts, 307

Pachymeningitis, externa, 331, 377

Paget’s disease, 359, 431

Pancreas, 244
degenerations, 250
tumors, 259

Pancreatitis, 250

Parasites, see animal parasites, 614

Parovarian cyst, 307

Pasteurelloses, 597

Pearl disease, 491, 501, 505

Pellagra, 441

Pelvis, comparative anatomy, 297–303

Penis, 313

Pericarditis, 53

Pericardium, position of effusion in, 54

Periosteitis, hypertrophic, 346

Periproventricular worms, 648

Perisplenitis, 131

Peritoneum, 260
tumors, 262

Peritonitis, 260

Pharyngitis, 168

Pharynx, 168

Phimosis, 313

Physaloptera turgida, 649
in opossums, 649

Plants, poisonous, 459

Pleura, 163

Pleuritis, 164

Pneumonia, 149
broncho, 152
fibrinous, 151, 153
in Aves, 153
origins of, 154
lobar, 151

Pneumonokoniosis, 159

Pneumonyssus foxi, 647

Poisonous plants, 459

Poliomyelitis, 380

Prostate gland, 313
enlargements of, 314
tuberculosis of, 315
tumors of, 314

Proventricle, 171
worms in, 172, 640

Psittacosis, 208, 597

Pyelonephritis, 277

Quail disease, 608

Rabies, 602

Rachitis, 349, 429

Rectum, prolapse of, 218

Reproductive organs, female, 287
male, 317

Respiratory tract, 134

Rhinitis, 135

Rickets, 349, 429

Renal calculi, 282

Salpingitis fallopii, 305

Santonin, 657

Sarcoma, 471, 474

Scurvy, 440

Seminal vesicles, 315

Sinusitis, 135

Skeleton, 343

Spinal cord, 373

Spiroptera incerta, 638, 640
detection, 640
eradication, 640
in parrots, 172, 208, 640

Spiropteriasis, 172, 640

Spleen, 114, 122
amyloid, 128
congestions, 125
enlargements, 124
hemorrhage, 125
inflammation, 126
in anemia, 130
in hepatic cirrhosis, 130
necrosis, 130
size, 124
tuberculosis of, 132

Squirrel monkeys, parasites of, 645

Starvation, 425

Stomach, 174
tumors of, 176
ulcers of, 175

Streptothricosis, 567

Suprarenal body, 336

Syngamus trachealis, 140, 650

Tænia echinococcus, 647

Tape worms, 637
in liver, 650

Temperature of monkeys, 520–528

Testes, 313
tumors of, 313

Tetanus, 602

Thrombosis, 69

Thymol, 657

Thymus, 120, 336

Thyroid body, 316
atrophy of, 330
hyperplasia of, 325
size of, 318
tumors of, 333

Tonsils, 115, 138

Trachea, 140

Tropidocerca contorta, 649

Tubercle bacillus, types of, 513

Tuberculin test on monkeys, 518
other animals, 549
dose, 529
effect on kidneys, 548
eye, 546
reaction, 530
skin, 546

Tuberculoma, 505

Tuberculosis of brain, 378
avian characters, 503, 512
Carnivora, 498
control, 514–548
diagnosis of, 514
discovery during life, 514
distribution in birds, 504

Tuberculosis of eye, 402
gelatinous, 504
histology, 510
hygiene, 516
in Aves, 503
in Mammalia, 492
in Primates, 492
in various avian orders 506–510
incidence, 489
intestinal in birds, 505
Lemures, 495
lymph nodes, 121, 494
nonsusceptible animals, 490
ordinate characters, 492
frequency, 489
pathological type, 490
Proboscidea, 502
Rodentia, 499
routes of infection, 485

Tuberculosis, sanitation of cages, 516
susceptible animals, 490, 515–517
Ungulata, 500
visceral distribution, 491

Tumors, see neoplasms

Ulcer, gastric, 175

Uncinaria, 643

Uremia, 281

Urethra, 315

Uterus, comparative anatomy, 287
inflammation, 305
tumors of, 308

Vitamins, 438

Waterfowl epizootic, 604

Zoological list, 43

A LIST OF THE PUBLICATIONS FROM THE LABORATORY OF COMPARATIVE PATHOLOGY
OF THE PHILADELPHIA ZOOLOGICAL SOCIETY 1909–1923

1. Results of Tuberculin Tests in Monkeys at the Philadelphia
Zoological Garden, by C. Y. White, M.D. and Herbert Fox, M.D.
_The Archives of Internal Medicine_, December, 1909, Vol. 4, pp.
517–527, Chicago, Illinois.

2. Note on the Occurrence of a Ciliate (_Opalinopsis nucleolobata,
n.s._) in the Liver of a Mammal (_Canis latrans_), by Allen J.
Smith, M.D. and Herbert Fox, M.D. _University of Pennsylvania
Medical Bulletin_, February, 1909, Philadelphia, Pennsylvania.

3. The Tuberculin Test in Monkeys: with Notes on the Temperature of
Mammals, by Arthur Erwin Brown, D.Sc., C.M.Z.S., Sec. Zool.
Soc., Phila. _Proceedings of the Zoological Society of London_,
1909, pp. 81–90.

4. Observations on the Occurrence of Neoplasms in Wild Animals, by C.
Y. White, M.D. and Herbert Fox, M.D. _Proceedings of the
Pathological Society of Philadelphia_, February, 1910.

5. Observations on the Comparative Anatomy of the Female Genitalia,
by Edward A. Schumann, M.D. _American Journal of Obstetrics and
Diseases of Women and Children_, Vol. LXIV, No. 4, 1911, New
York.

6. Observations Upon Neoplasms in Wild Animals in the Philadelphia
Zoological Garden, by Herbert Fox, M.D. _The Journal of
Pathology and Bacteriology_, Vol. XVII. (1912), pp. 217–231.
England.

7. A Study of Metazoan Parasites Found in the Philadelphia Zoological
Garden, by Fred D. Weidman, M.D. _Proceedings of the Academy of
Natural Sciences of Philadelphia_, March, 1913, pp. 126 to 151,
Philadelphia, Penna.

8. The Pathology of the Thyroid Gland in Wild Animals, by Herbert
Fox, M.D. _Journal of Comparative Pathology and Therapeutics_,
Vol. 27, p. 23. Edinburgh, Scotland.

9. The Mechanism of Labor From the Standpoint of Comparative Anatomy,
With a Report of Cases of Dystocia in Wild Animals, by Edward A.
Schumann, M.D. _American Journal of Obstetrics and Diseases of
Women and Children_, Vol. LXIX, No. 3, 1914, New York.

10. Cirrhosis of the Liver in Wild Animals, by Herbert Fox, M.D. _New
York Medical Journal_, December 19, 1914.

11. The Dynamics of the Female Pelvis; Its Evolution and Architecture
with Respect to Function, by Edward A. Schumann, M.D. _American
Journal of Obstetrics and Diseases of Women and Children_, Vol.
LXXI, No. 1, 1915, New York.

12. _Pneumonyssus foxi, Nov. Sp_. An Arachnid Parasitic in the Lung of
a Monkey (_Macacus rhesus_), by Fred D. Weidman, M.D. _Journal
of Parasitology_, September, 1915, Vol. II, pp. 27–45, Urbana,
Illinois.

13. _Cytoleichus penrosei_, A New Arachnid Parasite Found in the
Diseased Lungs of a Prairie Dog, (_Cynomys ludovicianus_).
_Journal of Parasitology_, December, 1916, Vol. III, pp. 82–89,
Urbana, Illinois. Fred D. Weidman, M.D.

14. A Method of Obtaining Duplicate Reconstructions from the One
Series of Wax Plates, by Fred D. Weidman, M.D. _New York Medical
Journal_, March 3, 1917, New York.

15. Papers: Read at the Meeting of the Pathological Society at the
Philadelphia Zoological Garden.

Pancreatitis in Wild Animals, by Herbert Fox, M.D.

Report of an Enzootic of Parasitic Proventricular Worms
(_Spiroptera incerta_, Smith) of Parrots, with Control of Same,
by Fred D. Weidman, M.D.

_Coccidium bigeminum_, Stiles, in Swift Foxes (habitat Western U.
S.), by Fred D. Weidman, M.D.

Distribution of Uncinaria Among the Lower Animals, by Fred D.
Weidman, M.D.

An Arachnoid (_Pneumotuber macaci_, Landois and Hœpke?) Parasitic
in the Lungs of a Monkey (_Macacus rhesus_), by Fred D. Weidman,
M.D.

A Note Upon the Lesions of the Female Genitalia in Wild Animals,
by Edward A. Shumann, M.D.

Amblyopia in a Young Monkey (_Macacus nemestrinus_), by H. M.
Langdon, M.D. and W. B. Cadawalder, M.D.

Remarks on Examinations of a Series of Brains, by W. B.
Cadawalder, M.D.

_Journal of Comparative Pathology and Therapeutics_, December,
1915, Vol. XXVIII, Part 4, pp. 298–336, Edinburgh, Scotland.

16. Reversionary Pseudobile Canaliculi Formation in the Cirrhotic
Liver of a Vulpine Phalanger, by Fred D. Weidman, M.D. _New York
Medical Journal_, March 9, 1918, New York.

17. A Contribution to the Anatomy and Embryology of _Cladorchis_
(_Stichorchis_) _Subtriquestrus_, Rudolphi, 1814 (Fischoeder,
1901), by Fred D. Weidman, M.D. _Parasitology_, Vol. X, No. 2,
January 22, 1918, Cambridge University Press, London, England.

18. Nutritive and Blood Changes in Rats on Cancer-Inhibiting and
Cancer-Stimulating Diets, by E. P. Corson-White, M.D.
_Pennsylvania Medical Journal_, March, 1919, Vol. XXII, p. 348,
Athens, Penna.

19. Pemphigus in an Orang Utan Infested with Strongyloides
(intestinalis?) and Dying from Advanced Tuberculosis, by Fred D.
Weidman, M.D. _Journal of Cutaneous Diseases_, March, 1919, Vol.
XXXVII, pp. 169–173, Chicago, Ill.

20. Arteriosclerosis in Wild Animals, by Herbert Fox, M.D. _American
Journal of Medical Sciences_, June, 1920, No. 6, Vol. CLIX, p.
821, Philadelphia, Penna.

21. Osteomalacia in Wild Animals, by E. P. Corson-White, M.D.
_Archives of Internal Medicine_, November, 1922, Vol. 30, pp.
620–628, Chicago, Illinois.

22. Osteitis Deformans in Monkeys, by E. P. Corson-White, M.D.
_Archives of Internal Medicine_, December, 1922, Vol. 30, pp.
790–796, Chicago, Illinois.

23. Certain Dermatoses of Monkeys and an Ape, by Fred D. Weidman, M.D.
_Archives of Dermatology and Syphilology_, March, 1923, Vol. 7,
pp. 289–302, Chicago, Illinois.

24. Acute Papular and Desquamative Exanthem in an Orang Utan, by
Herbert Fox, M.D., and Fred D. Weidman, M.D. _Archives of
Dermatology and Syphilology_, April, 1923, Vol. 7, pp. 462–464,
Chicago, Illinois.

-----

Footnote 1:

Those who are interested in the subject of disease in its effect on
evolution are referred to Morley Roberts, _Proceedings, Zoological
Society, London_, 1918, p. 247.

Footnote 2:

_Proceedings, Zoological Society, London_, 1911.

Footnote 3:

_Proceedings, Zoological Society, London_, 1911, p. 425.

Footnote 4:

_Proceedings, Zoological Society, London_, 1911, p. 620.

Footnote 5:

_Br. Med. Jour._, 1910, 2, 1161.

Footnote 6:

_Proc. London Zool. Soc._, 1907.

Footnote 7:

Total is the number of individual animals showing lesions, not the sum
of the listed changes.

Footnote 8:

_Comptes Rendus Soc. Biol._, T, 62–206.

Footnote 9:

This is done by determining the percentages of hypertrophy and
dilatation for the total number of each class examined at autopsy.

Footnote 10:

_Arch. für. Ges. Physiologie_, 1908, 125, 507

Footnote 11:

dal Piaz: Papers from the Department of Anatomy, University of
California, 1912. Bergmann: _Dissertation_, Munich, 1884. Loer: _Arch.
f. die gesamte Physiologie_, 1911, V. 140–293. Grober: _Arch. f. die
gesamte Physiologie_, 1908, V. 125–507. Grober: _Deutsch Archiv f.
Klin. Med._, 1907, V. 91, 502. Welcher and Brandt: _Arch. für
Anthropologie_, 1903, V. 28. Vierordt: _Tabellen_, 1906. Parrot:
_Zoologischer Jahresbericht_, 1893. Hasenfeld and Romberg: _Arch. f.
Exp. Path. und Pharmacol._, 1897, V. 39–333. Joseph: _Jour. Exp.
Med._, 1908, V. 10–521.

Footnote 12:

These values are obtained in part from the literature, in part from
our own specimens. At this laboratory the hearts of animals killed or
dying from a short illness, organs showing no pathological change,
were removed by cutting at the base of the vessels, washed free of
blood and weighed. The weight of the whole animal was obtained after
death.

Footnote 13:

These figures are obtained by determining mathematically the
percentage of each feature in each class and then reducing the numbers
to their lowest value.

Footnote 14:

_Verh. deutsch Path. Gesel._, 1906, X, 149.

Footnote 15:

With Coronary sclerosis only.

Footnote 16:

With Coronary sclerosis only.

Footnote 17:

_Proc. London Zool. Soc._, 1916.

Footnote 18:

_The Leucoses of Fowls_, London, 1922.

Footnote 19:

Lubarsch-Ostertag, _Ergeb. aus der Allg. Path._, 1908.

Footnote 20:

Vide Sisson’s _Veterinary Anatomy_ and Owen’s _Anatomy of the
Vertebrates_.

Footnote 21:

Ball, _Jour. Vet._, 1907.

Footnote 22:

See Magnan, _Compt. Rendus d. l’ Acad. de Science_, 1910 and 1911,
Vol. 150, 151, 152.

Footnote 23:

_C. R. Soc. de Biologie_, Paris, T. 73–526. _Bull. Mus. Hist. Nat.,
Paris Ann._, 1911, 492 et seq.

Footnote 24:

See Woodland, _Proc. London Zool. Soc._, 1906, and MacLeod, _Chemical
and Physiological Medicine_, Chicago, 1923.

Footnote 25:

_Proc. Zool. Soc. London_, 1905.

Footnote 26:

_Bull. Soc. Anat._, 1898, 73, 491

Footnote 27:

_Amer. Med._, 1903, 996

Footnote 28:

_Surg. Gyn. and Obst._, 1919, 28, p. 529.

Footnote 29:

_Jour. A.M.A._, 1921, 77, 194.

Footnote 30:

_Ibid._, 197.

Footnote 31:

Garrod, _Schorstein Lect._, 1920.

Footnote 32:

_Anatomical Record_, 1917, 13, p. 305, On the morphology of the renal
tubule in the vertebrates.

Footnote 33:

Policard, _C. R. Assoc. Anat._, 1910, 12, 57.

Footnote 34:

Huber, _Anat. Record_, 1916, 10, 201.

Footnote 35:

_Bull. Mus. Hist. Nat._, 1911, 493 and 1912, 527, and C. R. Acad. Sc.,
155, 182.

Footnote 36:

_C. R. Soc. Biol._, 1898, 5, 188.

Footnote 37:

_Monatsh._, 1893.

Footnote 38:

_Inaug. Diss. Giessen_, 1911.

Footnote 39:

_Arch. f. Tierheilk._, V. 38–99.

Footnote 40:

Comparative Anatomy of the Female Genitalia, _Am. Jour. of Obstet._,
Vol. LXIV, No. 4, 1914. Mechanism of Labor from a Comparative
Standpoint, _Ibid._, Vol. LXIX, No. 4, 1914. Dynamics of the Female
Pelvis, its Evolution, etc., _Ibid._, Vol. LXXI, No. 1, 1915.

Footnote 41:

_Proc. L. Z. Soc._, 1919, p. 16.

Footnote 42:

_Journ. Phys._, Vol. 34, 295.

Footnote 43:

_Am. Jour. Phys._, Vol. 30, 129.

Footnote 44:

Carlson, Rooks and McKie, _Loc. cit._

Footnote 45:

Vincent and Jolly, _Loc. cit._

Footnote 46:

See Blair and Brooks, Osteomalacia of Primates in Captivity, _Ninth
Annual Report, New York Zoological Society_, 1904, p. 135.

Footnote 47:

Campbell and Cleland, _Jour. Comp. Path. and Ther._, Vol. 32, p. 95.

Footnote 48:

_Med. Chir. Trans._, Vol. 60, 37, 1877.

Footnote 49:

_These de Lyon_, 1901.

Footnote 50:

_Verein Freibürger Aerzte_, May, 1902.

Footnote 51:

_Arch. f. Wiss. u. Prak. Tierhk._, Vol. 36, 652, 1910, and Vol. 39,
164, 1913.

Footnote 52:

_Vet. Med. Inaug. Diss. Giessen_, 1913.

Footnote 53:

_Traite d’ Anatomie Path._, 1883.

Footnote 54:

_Jour. Med. Res._, Vol. 24, 43, 1911.

Footnote 55:

_Publ. Jefferson Med. College_, Vol. 6, 1, 1915.

Footnote 56:

We have observed later, however, one case with very definite
degenerative arterial disease; it will be discussed under the
affections of the eye since the most definite and indeed only lasting
sign of trouble was amblyopia, the attack being ushered in by a
nondescript fit.

Footnote 57:

_Chemistry of the Proteins_, Mann.

Footnote 58:

_Ann. Inst. Past._, 1899, XIII, 558, and _Skandinavisches Arch. f.
Physiol._, 1904, XVI, 249.

Footnote 59:

_Skandinavisches Arch. für Physiologie_, Vol. 17, p. 211, 1905.

Footnote 60:

_Jour. Physiologie et Path._, Vol. 14, 108, 1912.

Footnote 61:

_Carnegie Institute Publication_, No. 203, p. 247, 1915.

Footnote 62:

_Jour. Biol. Chem._, Vol. 14, p. 59, 1913.

Footnote 63:

_Publication of the Jefferson Medical College and Hospital_, Vol. 6,
p. 1, 1915.

Footnote 64:

_These de Lyon_, 1901.

Footnote 65:

_Verein Freiburger Aerzte_, May 30, 1902.

Footnote 66:

_Vet. Med. Inaug. Diss. Giessen_, 1913.

Footnote 67:

_Chemistry of Food and Nutrition_, Macmillan, 1918.

Footnote 68:

Ohio Agricultural Experiment Station Bull., 295.

Footnote 69:

_Skandinavisches Archiv. f. Physiologie_, Vol. 17, p. 211, 1905.

Footnote 70:

_Bull._, 185, Experiment Station, U. S. Dept. Agriculture, 1907.

Footnote 71:

_Physiological and Pathological Chemistry_, Blakiston, 1902.

Footnote 72:

_Journ. Physiol._, 1912, XLIV, 425.

Footnote 73:

Die Vitamine und ihre Bedeutung für die Physiologie und Pathologie mit
besonderer Berücksichtigung der Avitaminoses, Wiesbaden, 1914.

Footnote 74:

_Newer Knowledge of Nutrition_, Macmillan, 1919.

Footnote 75:

_Bull._, 34, Bureau of Amer. Ethnology.

Footnote 76:

_Jahrhuch. Kinderheilk._, 1904, LIX, 175.

Footnote 77:

_Journ. Am. Med. Assoc._, 1917, LXVIII, 1516.

Footnote 78:

_Arch. Path. Anat._, 1897, CXLVIII, 523.

Footnote 79:

_Lancet_, London, March 12, 1910, 733.

Footnote 80:

_Lancet_, London, 1911, II, 1266.

Footnote 81:

_Bull._, Dept. of Agriculture, Dec. 13, 1915.

Footnote 82:

Bureau of Animal Industry, 1895–96, 172.

Footnote 83:

_Z. Hyg. u. Infektionskrankh._, 1913, LXXV, 334.

Footnote 84:

_Jour. Biol. Chem._, 1917, XXXI, 229.

Footnote 85:

_Jour. Infect. Dis._, 1916, XIX, 478.

Footnote 86:

_Jour. A.M.A._, 1922, 79, 2132.

Footnote 87:

_Pflüger’s Arch._, 1909 (129), 63.

Footnote 88:

_Chemical Pathology_, Philadelphia, 1918.

Footnote 89:

These botanical names are taken from Chestnut’s _Poisonous Plants of
America._

Footnote 90:

_Textbook of Histology_, 1920.

Footnote 91:

_Zeitch. für Krebsforsch_, Vol. 15, p. 1.

Footnote 92:

_Proceed. Phila. Path. Soc._, 1910, and _Journal of Pathology and
Bacteriology_, Vol. XVII, 1912.

Footnote 93:

Figures in parentheses are numbers of animals with captivity known.

Footnote 94:

See Gould’s _Birds_, Vol. II, p. 83.

Footnote 95:

_Am. Jour. Med. Soc._, 1907, 133–769.

Footnote 96:

_Jour. Path. and Bact._, Vol. XVII, 1912.

Footnote 97:

Totals and percentages for class, including all members.

Footnote 98:

Grand Totals, all autopsies.

Footnote 99:

Totals used for analysis after deduction of cases insufficiently
described.

Footnote 100:

_Rev. de Med. Vet._ T. 89, p. 221.

Footnote 101:

White and Fox, _Archives of Internal Medicine_, 1909, Vol. IV, p. 517.

Footnote 102:

The temperature in the axilla is often .5°F. higher than by rectum,
but the difficulties of the axillary method render it impracticable.

Footnote 103:

A. E. Brown, _Proc. London Zool. Soc._, June, 1909, p. 81.

Footnote 104:

Simpson and Galbraith, _Trans. Royal Soc._, Edinburgh, XIV, p. 1, 65,
1906.

Footnote 105:

This term will be used in the following pages to mention the organism
since by many persons it is better known than Nocardia and moreover
describes the form better. I believe genus Nocardia is the correct
nomenclature for reasons given on a subsequent page.

Footnote 106:

Those interested in the investigation of the cause of Blackhead are
referred to the recent literature by Tyzzer and by Smith, in the
_Jour. of Exp. Med._ and _Jour. of Med. Research_, 1918–1922.

Footnote 107:

There are certain exceptions to this, as with Nicoll’s (_Proc. Zool.
Soc. London_, 1912, p. 858) careful search for trematodes with sieves,
but this means a separate research, and is incompatible with the all-
round, general policies of present routine laboratory organization.

Footnote 108:

_Phila. Zool. Soc. Rep._, 1920, p. 28.

Footnote 109:

_Proc. Zool. Soc. London_, 1910, p. 134.

Footnote 110:

_Proc. Zool. Soc. London_, 1905, p. 252.

Footnote 111:

_Phila. Zool. Soc. Rep._, 1920, p. 29.

Footnote 112:

_Phila. Zool. Soc. Rep._, 1921, p. 31.

Footnote 113:

_Proc. Zool. Soc. London_, 1919, p. 15.

Footnote 114:

_Proc. Zool. Soc. London_, 1919, p. 15.

Footnote 115:

_Phila. Zool. Soc. Rep._, 1916–1921.

Footnote 116:

_Journal of Parasit._, June, 1921, p. 194.

Footnote 117:

_Proc. Zool. Soc. London_, 1910, p. 147.

Footnote 118:

Fantham, _Proc. Zool. Soc. London_, 1910, p. 672.

Footnote 119: