SECTION VI. The Respiratory System and Its Related Structures

THE RESPIRATORY SYSTEM AND ITS RELATED STRUCTURES

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.

RHINITIS, SINUSITIS.

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. 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 mammals 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 due 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.

MYCOSIS.

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.

There 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).

LARYNX.

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 which 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.

LARYNGITIS.

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 was 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 Ungulata, they have only been seen once within the tracheal tube.

THE BRONCHI.

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.

BRONCHITIS.

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.

TABLE 8. Showing the Percentage Incidence of Bronchitis and of Parasites in the Autopsies upon the Various Orders. ════════════╤═══════════════════╤═══════════════════╤═══════════════════ Orders │ Simple Bronchitis │ Verminous │Inactive Parasites │ │ Bronchitis and │of Lung (Encysted) │ │ Pneumonitis │ &c. ────────────┼─────────┬─────────┼─────────┬─────────┼─────────┬───────── „ │ Cases │Per cent.│ Cases │Per cent.│ Cases │Per cent. ────────────┼─────────┼─────────┼─────────┼─────────┼─────────┼───────── Primates │ 7│ 1.4│ 3│ .6│ 5│ 1. Lemures │ │ │ │ │ 1│ 1.2 Carnivora │ 14│ 2.9│ 8│ 1.6│ 8│ 1.6 Insectivora │ │ │ │ │ │ Chiroptera │ │ │ │ │ │ Rodentia │ │ │ 2│ 1.│ │ Ungulata │ 5│ 1.3│ 2│ .5│ 10│ 2.7 Proboscidea │ │ │ │ │ │ Hyracoidea │ │ │ │ │ │ Edentata │ │ │ │ │ 2│ 12.5 Marsupialia │ 3│ 1.7│ 2│ 1.1│ 3│ 1.7 Monotremata │ │ │ │ │ │ │ │ │ │ │ │ Passeres │ 4│ .29│ 7│ .5│ 2│ .16 Picariæ │ │ │ │ │ │ Striges │ │ │ │ │ │ Psittaci │ 4│ .58│ │ │ │ Accipitres │ 1│ .5│ │ │ │ Columbæ │ │ │ │ │ │ Galli │ │ │ 1│ .3│ │ Hemipodii │ │ │ │ │ │ Fulicariæ │ │ │ │ │ │ Alectorides │ │ │ │ │ │ Limicolæ │ │ │ │ │ │ Gaviæ │ │ │ │ │ │ Impennes │ │ │ │ │ │ Steganopodes│ │ │ │ │ │ Herodiones │ 1│ 1.│ │ │ 1│ 1. Odontoglossæ│ │ │ │ │ │ Palamedes │ │ │ │ │ │ Anseres │ 2│ .67│ 3│ 1.│ │ Struthiones │ 1│ 3.3│ │ │ │ ────────────┴─────────┴─────────┴─────────┴─────────┴─────────┴───────── For meaning of italics see footnote Table 1.

A 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.

To 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.

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 supporting 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 some 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 LUNGS.

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 some 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 lungs 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.

CONGESTION OF LUNGS.

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.

I 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.

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 stood 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.

TABLE 9. Showing the Number of Cases of the Various Forms of Pneumonia Found in Each of the Orders. ════════════╤═════════╤═════════╤═══════╤══════╤══════════╤═══════╤═══════════ │Fibrinous│Catarrhal│ Acute │Septic│Hypostatic│Chronic│Pleurogenic │ Lobar │ │Inter- │ │ │Inter- │ │ │ │stitial│ │ │stitial│ ────────────┼─────────┼─────────┼───────┼──────┼──────────┼───────┼─────────── Primates │ 4│ 22│ 2│ 1│ 1│ 2│ 2 Lemures │ 1│ 3│ │ │ │ │ Carnivora │ 1│ 34│ │ 4│ │ 1│ Insectivora │ │ │ │ │ │ │ Chiroptera │ │ │ │ │ │ │ Rodentia │ │ 6│ │ 3│ │ │ Ungulata │ │ 14│ │ 5│ 1│ 1│ Proboscidea │ │ 1│ │ │ │ │ Hyracoidea │ │ │ │ │ │ │ Edentata │ │ 1│ │ │ │ │ Marsupialia │ │ 13│ 1│ │ 1│ │ Monotremata │ │ │ │ │ │ │ │ │ │ │ │ │ │ Passeres │ 1│ 59│ 2│ 2│ │ │ Picariæ │ │ │ │ │ │ │ 1 Striges │ │ 3│ │ │ │ │ 1 Psittaci │ 1│ 15│ │ │ │ 1│ Accipitres │ │ 1│ │ │ │ │ Columbæ │ │ 2│ │ │ │ │ Galli │ │ 2│ │ │ │ │ Hemopodii │ │ │ │ │ │ │ Fulicariæ │ │ 1│ │ │ │ │ Alectorides │ │ │ │ │ │ │ Limicolæ │ │ │ │ │ │ │ Gaviæ │ │ │ │ │ │ │ Impennes │ │ │ │ │ │ │ Steganopodes│ │ │ │ │ │ │ Herodiones │ 1│ │ │ │ │ │ Odontoglossæ│ │ │ │ │ │ │ Palamedes │ │ │ │ │ │ │ Anseres │ 1│ │ │ │ │ │ Struthiones │ │ │ │ │ │ │ ────────────┴─────────┴─────────┴───────┴──────┴──────────┴───────┴───────────

Primates 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 shows 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. ]

Marsupialia 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 within 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.

PRODUCTION OF INSULAR PNEUMONIA IN BIRDS.

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. ]

The 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 LUNG.

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.

TABLE 10.

Table giving Analysis of 20 Mammalian and 3 Avian Cases of Abscess and Gangrene of the Lung

════════════╤═══════════════╤════════════════╤════════ Animal │ Causative │ Pneumonia, │Abscess │condition upper│septic or other │ or │ respiratory │ │Gangrene │ tract │ │ ────────────┼───────────────┼────────────────┼──────── Sooty │Negative │Catarrhal │Gangrene Mangabey │ │pneumonia │ Cercocebus │ │ │ fuliginosus │ │ │ │ │ │ Rhesus │Negative │Septic from │Abscess Macaque │ │suppurating │ Macacus │ │gland │ rhesus │ │ │ Am. Wild Cat│Aspiration │ │Gangrene Felis ruffus│vomitus from │ │ │violent │ │ │gastroenteritis│ │ │ │ │ │ │ │ │ │ │ Puma Felis │Acute purulent │No │Abscess concolor │nasopharyngitis│ │and │ │ │gangrene │ │ │ │ │ │ Ichneumon │Negative │Sepsis, scalp │Abscess Herpestes │ │wound │ mungo │ │ │ │ │ │ │ │ │ Raccoon │Negative │Pneumonia │Abscess Procyon │ │followed by │ lotor │ │sepsis │ │ │ │ │ │ │ Skunk │Cellulitis face│Sepsis, very │Abscess Mephitis │and neck │mild │ mephitica │ │ │ Puma Felis │Perforating │Secondary │Abscess concolor │abscess around │terminal │ │jaw │pneumonia, │ │ │sepsis │ │ │ │ │ │ │ Porcupine │Negative │Enteritis, no │Abscess Erethizon │ │special sepsis │ dorsatus │ │ │ │ │ │ │ │ │ │ │ │ Kangaroo Rat│Negative │Right sided │Abscess Perodipus │ │bronchopneumonia│ richardsoni │ │ │ │ │ │ Squirrel │Abscess under │No │Abscess Sciurus p. │eye and in │ │ carolinensis│masseter muscle│ │ │ │ │ │ │ │ │ │ │ Mule Deer. │Actinomycosis? │Arthritis. │Abscess Mazama │nasopharynx │Myositis │and hemionus │ │Tenosynovitis │gangrene │ │ │ │ │ │ Axis Deer. │Negative │Negative │Abscess Cervus axis │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ Tapir. │Abscess of │Died from │Abscess Tapirus │parotid │enteritis │ indicus │ │ │ │ │ │ │ │ │ │ │ │ Gazelle. │Negative │Sepsis from │Abscess Gazella │ │infected wound │ isabella │ │ │ │ │ │ │ │ │ Kangaroo. │Negative │Catarrhal │Abscess Macropus │ │pneumonia │and rufus │ │ │gangrene │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ Kangaroo. │Kangaroo │Sepsis │Abscess Macropus │mycosis of jaw │ │ rufus │ │ │ │ │ │ Kangaroo. │Kangaroo │ │Abscess Macropus │mycosis of jaw │ │ giganteus │ │ │ │ │ │ Kangaroo. │Negative │Sepsis from │Abscess Macropus │ │infected wound │ robustus │ │ │ Devil. │Negative │Negative sepsis │Abscess Sarcophilus │ │ │ ursinus │ │ │ │ │ │ │ │ │ Crow. │Negative │Filaria in │Abscess Gymnorhina │ │blood? │ leuconota │ │ │ Heron. Ardea│Negative │Negative │Abscess tricolor │ │ │ ruficollis │ │ │ │ │ │ │ │ │ Goose. Anser│Syngamus in │Negative │Abscess fabalis │trachea │ │ │ │ │ │ │ │ │ │ │ │ │ │ ────────────┴───────────────┴────────────────┴────────

════════════╤═════════╤══════════════╤══════════════ Animal │Single or│ Position │ Bacteria │Multiple │ │ │ │ │ │ │ │ ────────────┼─────────┼──────────────┼────────────── Sooty │Massive │Upper part │Streptothrix, Mangabey │single │lower lobe and│necrosis Cercocebus │ │adherent part │bacillus. fuliginosus │ │upper lobes │ │ │left side │ Rhesus │Single │Occupied │ Macaque │ │nearly all │ Macacus │ │right middle │ rhesus │ │lobe │ Am. Wild Cat│Bilateral│Right middle │ Felis ruffus│ │lobe, left │ │ │lower lobe, │ │ │left bronchus │ │ │ruptured, │ │ │right middle │ │ │lobe ruptured │ Puma Felis │Bilateral│Right upper │Streptococcus concolor │ │and left lower│pyogenes. │ │lobe abscesses│ │ │biggest, right│ │ │middle also │ Ichneumon │Bilateral│Scattered │ Herpestes │ │small │ mungo │ │abscesses, │ │ │under pleura │ │ │especially │ Raccoon │Bilateral│Probably all │ Procyon │ │lobes, right │ lotor │ │middle │ │ │contains │ │ │largest │ Skunk │Single │Left lower │ Mephitis │ │lobe, single │ mephitica │ │small │ Puma Felis │Bilateral│Numerous small│ concolor │ │abscesses, │ │ │irregularly │ │ │scattered │ │ │through both │ │ │lungs │ Porcupine │Bilateral│Multiple small│ Erethizon │ │scattered. │ dorsatus │ │Parasitic? No │ │ │notes │ │ │parasites or │ │ │bacteria │ Kangaroo Rat│Single │Left lower │ Perodipus │ │lobe, small │ richardsoni │ │abscess, │ │ │record scanty │ Squirrel │Multiple │Left lung │ Sciurus p. │ │scattered, │ carolinensis│ │small │ │ │abscesses, │ │ │parasites not │ │ │seen │ Mule Deer. │Bilateral│Scattered both│ Mazama │ │lobes under │ hemionus │ │pleura, upper │ │ │right inferior│ │ │tip gangrenous│ Axis Deer. │Single │Apparently │Streptothrix. Cervus axis │ │primary │ │ │streptothrix, │ │ │abscess in │ │ │cardiac tip of│ │ │upper lobe │ │ │with extension│ │ │toward hilum │ Tapir. │Bilateral│Multiple │Staphylococci. Tapirus │ │subpleural pus│ indicus │ │pockets, │ │ │surrounded by │ │ │catarrhal │ │ │pneumonia │ Gazelle. │Bilateral│Multiple │ Gazella │ │subpleural and│ isabella │ │internal, both│ │ │lungs about │ │ │the same │ Kangaroo. │Double │Lower middle │Pneumococci Macropus │left │left lobes, │streptothrix. rufus │ │seat of a │ │ │ruptured │ │ │gangrene │ │ │surrounded by │ │ │pneumonia, │ │ │right lung │ │ │pneumonic │ Kangaroo. │Bilateral│More on right │Streptothrix, Macropus │ │side, sharply │cocci. rufus │ │outlined │ │ │abscesses │ Kangaroo. │Single │Abscess and │Streptothrix Macropus │ │atelectasis, │ giganteus │ │right middle │ │ │lobe │ Kangaroo. │Single │Lower right │ Macropus │ │lobe │ robustus │ │ │ Devil. │Multiple │Largest middle│Probably Sarcophilus │ │of right lung,│streptothrix. ursinus │ │many small │ │ │scattered │ │ │abscesses. │ Crow. │Multiple │Scattered tiny│ Gymnorhina │ │abscesses, no │ leuconota │ │worms seen │ Heron. Ardea│Single │Upper pole, │ tricolor │ │right lung, no│ ruficollis │ │apparent │ │ │antecedent │ │ │cause │ Goose. Anser│Single │Lower half │ fabalis │ │right lung │ │ │occupied by │ │ │abscess, which│ │ │has penetrated│ │ │air sac │ ────────────┴─────────┴──────────────┴──────────────

The 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 carries 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.

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 of 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.

INFARCTION OF LUNG.

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 only 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.

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.

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 under the pleura and in the pulmonary 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.

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 should 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. ]

There 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).