TUBERCULOSIS.

Synonyms. Definition: infectious disease caused by bacillus, attended by productive inflammation, tubercles, necrotic degeneration, caseation, fibroid change, calcification or ulceration. Animals susceptible: python, salamander, carp, fish, birds, rodents, sheep, goats, solipeds, cattle, dogs, cats, apes, swine, wild ruminants, kangaroo, carnivora, cage birds, civilized (housed) man. Geographical distribution: with dense population, Central Europe, Britain, Eastern States; little in absence of cattle products—Scottish Western Isles, Iceland, Newfoundland, Greenland Highlands, Arctic North America, Northern Norway, Sweden, Lapland: open air life protects. Virulence: ancient records, modern, early antituberculous legislation, decimation of herds, researches of Vilemin, Gerlach, Chauveau, Semmer, Parrot, Tappeiner, etc. Bacillus tuberculosis: evolutionary changes, relation to actinomyces, 1.5 to 3.5μ by 0.2μ shorter and thicker in ox, solitary, exceptionally short chains, on blood serum may be filamentous, staining slow, carbolated fuchsin, technique, sections; biology, adaptation to environment, to genera, variation in same genus, experiments showing real identity of variant forms; vitality: in water human bacillus 50 to 70 days, bovine bacillus indefinitely, avian 117 days, dried sputa 9 months, cow’s lung 102 days, putrid material 43 days to years, survives gastric juice, sunlight kills in some hours, if in thin layer, day light 7 to 18 days, dry heat (212° F.) for an hour left living bacilli, moist heat 140° F. for 1 hour kills, low temperatures (−25° F.) fail, after 15 days in salt failed in rabbit, after 30 in Guinea pig. Chemical disinfectants. Accessory causes: racial vulnerability, close buildings, dark, foul, damp stables, poor scanty food, heavy milking, conformation, early breeding, inbreeding, age, predisposing diseases, traffic in animals, dairy extension, admission of tuberculous animals from other states, assorting tuberculous for sale in a given State, sale of sound from tuberculous herd, lack of indemnity for animals killed, private testing of herds and sale of tuberculous, accustoming to tuberculin test, antipyretics during tuberculin test, false certificates of tuberculin tests, feeding hogs on tuberculous offal, feeding calves and hogs on tuberculous milk, feeding hogs after tuberculous cattle, feeding from a common trough, dry, dusty stables, extension through vermin, flies and other insects carry virus. The tubercle: miliary, pinhead, conglomerate, proliferation of cells—tissue and leucocytes, in nests in stroma, giant cells in center, then epithelioid, then lymphoid, caseation, calcification, fibrosis, pearl disease. Localization: Cattle: pulmonary: miliary tuberculosis, aggregation into larger tubercles, caseated centres, fibroid, cretified, abscesses, vomicæ, complex infections, infiltrations, difference from broncho-pneumonia, lesions of different ages; pleural lesions; congestion, exudation, fringes, nodules, grapes, adhesions, caseations: bronchial and mediastinal glands, congestion, swelling, softening, induration, caseation, cretefaction: cardiac lesions: lesions of mouth and 399throat, pharyngeal glands: gastro-intestinal, peritoneal, mesenteric glandular; œsophagastoma; liver tubercle; splenic; pancreatic; genito-urinary; mammary; cerebral; spinal; orbital; skeletal; cutaneous; muscular; glandular; table of distribution. Swine: lesions: pharyngeal, intestinal, mesenteric, muscular, hepatic, splenic, glandular, pulmonary, skeletal, caseation, liquefaction. Horse: lesions: thoracic, abdominal, glandular, of serosæ, vertebræ, etc. Sheep and goat: lesions: thoracic, abdominal, glandular, hepatic, pharyngeal, facial, etc., verminous affections. Dog and Cat: lesions: respiratory, abdominal, pharyngeal, tonsillar, hepatic, pancreatic, splenic, skeletal, arthritic, cutaneous. Apes and Menagerie Animals: lesions. Chickens: lesions: intestines, liver, spleen, peritoneum: lungs and kidneys often escape. Pheasant: lesions: as in hens, centre zone has epithelioid cells, fibroid, cretefaction, amyloid degeneration. Parrot: lesions: eye, beak, tongue, palate, larynx, bones, joints, lungs, liver, intestines, muscles, skin. Primary and secondary infection, extension by lymphatics, blood channels, tonsils, inhalation, deglutition.

Synonyms. Consumption; Tabes; Scrofula; Pining; Grapes; Great White Plague, etc.

Definition. An infectious disease common to man and a large number of animals, caused by the bacillus tuberculosis, and characterized by a productive inflammation giving rise to small, rounded bodies (tubercles), or diffuse infiltration, with a tendency to necrotic degeneration, and caseation, or to fibroid degeneration (sclerosis), calcification or ulceration.

Animals susceptible. Tuberculosis comes near to being a panzoötic, since although reptiles, fishes, birds and some mammals do not readily contract it under normal conditions, yet under abnormal and debilitating conditions nearly all will succumb to it.

Reptiles. Sutton found tuberculosis in a python which was kept so warm in the London Zoological Gardens that a thermometer between its folds registered 85° F. Kráhl, Battaillon and Ferre cultivated the bacillus in frogs, Kráhl in snakes. Blauvelt found tuberculosis in a salamander. Lechner found it in amphibia.

Fishes. Broussais records the prevalence of tuberculosis in carp in a pond which received the sputa of a consumptive man. Under the skin were found rounded tumors, containing abundance of bacilli, that infected rabbits and Guinea pigs on which they were inoculated.

Birds. In birds of the farmyard—hens, pheasants, turkeys, ducks and pigeons—it is very frequent and often occurs as an 400epizoötic. While the tuberculosis of barnyard fowl is a manifest variety and not readily interchangeable with the varieties affecting the mammal, yet, with a special predisposition, it can be transferred and can then be conveyed from animal to animal in the new genus in which it has been implanted. That of cage birds is interchangeable with that of man.

Rodents. Guinea pigs have a strong susceptibility to tuberculosis, whether from human or bovine source, and rabbits for that of birds, and by continuous transmission through the body of the rodent, all alike seem to tend toward acquiring common characters. The Guinea-pig, therefore, has been especially availed of for the experimental transmission of tuberculosis, and, as the disease in them becomes acute and rapid in its progress, these subjects permit the multiplying of experiments in a short period. Rabbits are less vulnerable to the bovine or human form.

Sheep and goats, kept under usual conditions, show a remarkable immunity from tuberculosis, yet if directly inoculated an inherent susceptibility is easily shown. Habitual immunity may be in some degree due to their open air life, to the heavy winter fleece protecting them against chills, to the comparative absence of the heavy and continuous milk yield demanded of cows, to the more restricted development of the lymph plexuses in the lungs and elsewhere, and to the limited opportunity offered by the small tonsils for infection entrance.

The horse, ass and mule rarely contract tuberculosis casually, the more spacious stall, outdoor life, hard muscular condition, the very small tonsils, the exclusive nasal respiration, the paucity of connective tissue lymph plexuses, and the abundance of red globules, probably favor immunity. Yet on inoculation by Chauveau, Nocard and others, the horse readily succumbed to infection, generalization taking place more certainly than in the ox.

Cattle. The bovine races are remarkably subject to tuberculosis. This is probably due in part to the great amount of connective tissue lymph plexus in the lungs and elsewhere, the habit of using the mouth in hurried breathing, the deep, sudden inspiration through the mouth and over the tonsils that follows a cough, the habitual restricted size of the cow stables, the absence of individual separated stalls, the habit of feeding from the same trough with the cattle adjacent, the great drain of yearly breeding 401and heavy milking, the retention in the herd of old, failing cows for their milk product and high priced offspring, and the bovine habit of licking each other with the infected tongue. In many European cities and even in country districts the disease is very prevalent. In Copenhagen a few years ago 17.7 per cent. of all oxen and cows killed in the abattoirs were tuberculous; in Berlin 15 per cent.; in Holland 20 per cent.; in Pomerania and Bomberg 50 per cent.; in Hildesheim, Hanover, 50 per cent.; in Berlin dairies 75 per cent. (Ostertag): in Leipsic and Edinburgh 20 per cent. The great variation in the data for the different cities is suggestive of different inspection standards. American figures as given by the Bureau of Animal Industry are for Baltimore (mostly cows recently from the country) 2.5 to 3.5 per cent.; and for the packing centers (among 2,273,547 mostly fat steers, and therefore selected) 0.02 per cent. It is here largely a matter of locality and infection, I have seen large herds with 100 per cent. tuberculous, and extensive districts, in the north and especially in the south entirely free from the disease.

Dogs and cats in their natural condition rarely show the disease, but contract it readily on inoculation. Cadiot found 40 cases in 9,000 post mortems of dogs. The young are apparently more susceptible than the old, and primary lesions in the abdomen are common and suggest infection through the food. The majority belonged to consumptive persons, and gnawed the bones that had been first picked by the owner, and ate from his plate what he left. Jacobi records the case of a dog, with general tuberculosis, which habitually licked up the expectorations of his phthisical master.

Apes and Monkeys, in confinement, almost all die of tuberculosis.

Swine contract tuberculosis readily, the large tonsils, the habit of breathing through the mouth, and the abundance of connective tissue and lymph plexuses in the lungs and elsewhere contributing to this. Yet in them the affection is mainly a dietetic disease. Swine kept in the country and fed on vegetable food are rarely affected. In Saxony, where 17 per cent. of the cattle are tuberculous only a shade over one per cent. of swine were so, and in Baden only 0.02 per cent. In hogs raised on our western farms and corn-fed the proportion is much less. Yet in those fed on uncooked skim milk, kitchen scraps and the refuse of slaughterhouses 402in a raw state, tuberculosis becomes very common. In one case, in a large public institution, where the dairy herd was universally affected, and where, on their slaughter, their raw offal had been thrown to the hogs, I found that the latter were almost all tuberculous. Similarly, in feeding experiments, from the time of Gerlach, pigs and especially young pigs, have shown themselves to be very susceptible.

Among the less domesticated animals that contract tuberculosis may be named deer, elk, gazelle, antelope, camel, dromedary, giraffe, kangaroo, lion, tiger, jackal, jaguar, bear, arctic fox, rat, mouse and the common cage birds, etc. Fröhner found 36 per cent. of parrots affected in Berlin.

Man has long been recognized as standing in the front rank of susceptibility to tuberculosis. Yet even in his case the prevalence of the affection bears an intimate relation to his indoor life. In large cities post mortems often show that one-third have suffered, and that one-seventh and upward of the whole population die of tuberculosis. Natives of tropical islands and countries, living in the open air and apart from close association with civilized man, often escape entirely. In South Africa the herdsmen living in close buildings suffer encreasingly, while their cattle, kept constantly in the open pasture, escape.

Geographical Distribution. The prevalence of tuberculosis shows a direct relation to the opportunity for infection rather than to climate, latitude or altitude. It is the prevailing disease of civilized communities with dense populations, and especially in large cities where the general vitality is lowered and the crowded buildings give every opportunity for infection. It is preëminently the disease of Central Europe, of Great Britain and of our Eastern States, where there is the greatest activity in business, manufacture and commerce. Yet in the Scottish Hebrides, Iceland, Newfoundland, the Greenland Highlands, Arctic North America, the northern parts of Norway and Sweden, Lapland and Finland it is hardly known. The absence of commerce and cattle and the sparse population have much to do with this. The coasts of Greenland with their Danish stations have two-thirds of the population tuberculous (Cook); the Indians of Barrow’s Straits, when infected in 1899 by the frozen-in whalers, suffered from it as from a plague; in Christiana, Stockholm and St. 403Petersburg it is as prevalent as in the large cities of Central Europe. Elevated and dry climates have often been found to be free from the affection, yet it prevails inside the double windows of houses in the higher Alps, and has, within a generation established a notorious prevalence in Minnesota, Dakota and westward, as it has in Australia, mainly owing to the advent of consumptives who sought for health in the dry atmosphere. The hills and dry tablelands in North and South America, Africa and Asia which have acquired a reputation for salubrity, owe this largely to the sparse population and the absence of facilities for infection. In South Africa, in spite of the dry and genial climate, the disease is constantly encreasing in the human (housed) population. The sea-coasts, which are the seats of large cities and the centres of population and trade, are also the most extensively affected with tuberculosis—in the West Indian Islands, Panama, Nicaragua, Mexico, Yucatan, Columbia, Equador, Peru, Chili, Ceylon, Guinea coast—while the sparsely peopled highlands of the same countries are practically free.

What is true of man is equally so of cattle. In the Gulf states of this country, herds living in the open air are practically free from tuberculosis, while in New Orleans and other large cities, the cows shut up in the confined stables and yards, are as tuberculous as those of the great cities of the north. So in many districts in the northern states we find no bovine tuberculosis, while in others, differing in no essential particular as regards geological formation, altitude, exposure, and industrial use of the animal, a large proportion are affected.

Virulence. Tuberculosis has long been recognized as virulent. “It is indicated in the Mishna and other Jewish works as rendering the meat unfit for consumption, but to come to more modern times, we find that throughout the seventeenth and eighteenth centuries the flesh of tuberculous animals was excluded from human food, alike by the civil and ecclesiastical laws of Europe. Tuberculosis in cattle was erroneously identified with syphilis of man, which made a frightful extension in the end of the fifteenth century, spreading from the army of Charles VIII which had been engaged in the siege of Naples. This conviction lasted until it was disproved about 1782. Though mistaken in the identity of the two diseases, the fact that for centuries the common 404people and physicians both associated tuberculosis with a malady so notoriously contagious as syphilis, speaks strongly for the forcible evidence of contagion manifested at that time. Morgagni, who must have begun practice about 1700 A. D., testifies to the strong conviction of the contagious element in tuberculosis. Indeed it became a common practice to isolate the consumptive person from the public, and after his death to burn his clothes and sometimes even the house, or at least to subject them to a careful disinfection. It is recorded that in 1750, in Nancy, the magistrates ordered the burning, in the public square, of the personal property of a woman who had died of phthisis, from sleeping in the bed of another consumptive person.

“At Naples, a royal edict of September 20, 1782, prescribed the sequestration of the phthisical, the disinfection of the rooms, chattels, movables, books, etc., with vinegar, eau-de-vie, lemon juice, sea-water, fumigations, etc., under a penalty of three years at the galleys, or in the case of nobles, of three years imprisonment and a fine of 300 ducats. A physician who failed to report a case of consumption was fined 300 ducats for the first offense, and banishment for ten years in case of a second. Any one assisting in such evasion of the law was sent to prison for six months.

“Chateaubriand found that, in 1803, he could not sell his carriages in Rome, because Mme. Beaumont, who had died of consumption, had ridden in them three or four times. George Sand, who was with the phthisical Chopin in Minorca in 1839, was refused a lease of the house for the second month, and the price of repainting and purifying was demanded. Later, in Barcelona, they were assessed for the bed on which Chopin had slept, as the police regulations prescribed it should be burned.

“This was not a mere survival of vulgar prejudice. Jacobi tells us of a dog which died of consumption from eating the sputa of his phthisical master. Laennec, the discoverer of auscultation, and the great authority on pulmonary consumption, records that he himself contracted a tuberculous nodule, through a wound with a saw, while making a necropsy in a case of phthisis. Laennec died of tuberculosis later, although he seemed to have checked this lesion by caustics. Andral joins Laennec in enjoining the greatest caution and cleanliness in taking care of, or associating with persons having advanced tuberculosis.

405“Cullen, who started with a strong prejudice against the doctrine of contagion, leaves us the following instance of its occurrence: ‘A young man predisposed to phthisis married a Dutch girl of a sanguine temperament and good constitution. Some days after the marriage the woman lost her fresh color and was attacked by a bad cough; a month later she commenced spitting blood. The physician advised her not to sleep in the same bed with her husband, but she refused to follow his advice, and six months later she died of phthisis. The servant who took care of her and the domestic, who avoided, as far as possible, staying in the sick chamber, both died of consumption.’

“Wickmann, court physician in Hanover, in 1780, pronounces emphatically for contagion. In Zurich, at that time, one death in every six was from phthisis. The contagion of phthisis was slow in its operation, and was, therefore, less evident than that of plague, smallpox, scarlatina and other affections attended by a skin eruption, but it was no less real and deadly. It was also less frequently indirect, or carried from victim to victim by intermediate agents. He cited instances of the transmission of consumption from husband to wife and vice versa, and claimed that the marriage of a phthisical person should be legally prevented. As a means of preventing the disease, he proposed a strict surveillance of establishments for the sale of old clothes, and the avoidance of leaving infants with consumptives.

“Valsalvi and Sarconi refused to make necropsies of persons who had died of phthisis.

“Dr. Ruhling, of Gottingen, writing in 1774, of the disease in animals, says: ‘The malady is transmitted to sound animals by direct contact of animals standing side by side in the stall, and licking each other, and breathing the expired air direct from the diseased lungs; the frequenting of the same pastures will also serve to propagate it.’ In Krunitz’s encyclopedia, published in Berlin, in 1787, is the following: ‘The heifers show an ardent desire for the male, and remarkably enough, do not become pregnant, but part with the fruit of conception. When opened these animals show the first stomach, kidneys and surface of the lungs, covered with pustules like dried mulberries or in suppuration. The affection is contagious, and communicates itself from one animal to another by contact.’

406“Fromage, in the Dictionaire de Rozier, Article Phthisis, says: ‘Men of art are very much in accord that this malady is not contagious, but some stock owners think differently.’

“Huzard, who saw much of tuberculosis in the Parisian dairies in the concluding decade of the last century, said that most of the veterinarians looked upon the disease as contagious, and that some of the physicians believed the same of the phthisis of man.

“Dewar, speaking of his experience in Scotland in 1839, and succeeding years, in a particular herd, says: ‘The proprietor agreed to remove partition walls, and to make openings opposite one another in the outside walls, so that there might be a current of fresh air passing through. These alterations combined with cod liver oil, tonics and stimulants, may have prolonged life but yet no cure was effected, and that herd died out. I resorted to every precaution when new cattle were purchased to prevent infection; as I had an idea, even at that time, that the disease might be communicated from one to another when in immediate contact. The precautions adopted when fresh cattle were purchased had the desired effect, for in a few years afterward, they were as good a lot of cattle as any in the district. That herd left an impression on my mind that never can be effaced, and made me always dread the evil consequences of tuberculosis. Having practiced in the same locality, which is an extensive breeding and rearing district, I have seen several herds decimated. Though I have sometimes foretold the owner what he might expect, yet he did not believe me until so many were infected that the byres were infested with the fearful malady, and your remarks in regard to nose contamination are so true that I do not think it possible any can escape that are so exposed. I have also seen, as Grad has, the same stall infecting beast after beast until a thorough cleaning and disinfecting, with plenty of fresh air had removed all infection.’

“Spinola, writing in 1858, of bovine tuberculosis, gives contagion as a possible cause, and Lafosse, in 1867, says: ‘Physicians begin in imitation of Morgagni to believe in the contagion of phthisis. The facts published by Villemin appear to support this opinion, which has been held by our colleague, Dupont, of Bordeaux, for several years.’

“Cruzel in his work of date, 1868, is much more positive; he says: ‘This fœtid expired air, inhaled immediately by another 407cow upon a sound lung, gives the latter tuberculous infection. It is a matter of every day experience to the veterinarian. Two oxen or cows are kept in the same stable, take their food from a common rack or manger, lie in the same stall, and respire nose to nose. The one is, to all appearances, perfectly sound, the other is in as good a condition, and is vigorous, but it coughs from time to time, and its breath is foul. Soon we notice that the animal that does not cough, eats with less appetite, he loses flesh and soon he is unequivocally affected with the same malady as the first.’ The foregoing quotations show clearly that in spite of the misleading teachings of Broussais and others, the doctrine of contagion in tuberculosis could not be overcome, and that up to the time of the remarkable experiments of Villemin, in 1865, it maintained its hold upon the minds of extensive and careful observers. In animals, especially, the evidence was so frequent and clear, animal following animal in the same stall, and eating from the same infected manger, only to be infected in turn, and two animals stalled together, and licking the same manger with their prehensile tongues, transmitting the infection with certainty the one to the other, were facts that could not possibly be ignored. Other cattle in the same building might escape for a length of time, but the eating in common from the same fatal manger, by a tuberculous and a healthy animal, quickly sealed the fate of the latter.

“Physicians, too, who were compelled to investigate the causes of the extraordinary fatality from tuberculosis in the armies and navies, could not shut their eyes to the fact notwithstanding that they came to the task strongly prejudiced through education against the acceptance of contagion. Thus, Dr. Bryson, in his report to the Epidemiological Society, in 1860, on consumption in the several ships of the English navy on the Mediterranean station, says distinctly that the disease appeared to be propagated by contagion. Dr. Parkes, quoting this in his Practical Hygiene, says: ‘It may be inferred that pus cells were largely thrown off during coughing, and floating through the air, were received into the lungs of other persons. The production of phthisis in animals confirms this view. The case of monkeys in the zoological gardens, narrated by Dr. Arnot, is a striking instance. Cows in close stables frequently die of 408phthisis. But not only phthisis may reasonably be considered to have one of its modes of origin in the breathing of an atmosphere contaminated by respiration, but other lung diseases, bronchitis and pneumonia, appear also to be more common under such circumstances.’

Villemin in 1865, published his investigations in which he had produced tuberculosis in a great number of animals, by inserting particles of fresh tubercle or injecting the tuberculous sputa of man into the subcutaneous connective tissues, the peritoneum and the trachea. There resulted in nearly every case a chronic disease, the marked phenomena of which were caseated centers devolving from firm inflammatory nodules in the seat of inoculation, in the adjacent lymphatic glands, in the lungs, serous membrane, liver, spleen and kidneys. The centers of such nodules were at first transparent and grayish, but soon the center underwent necrobiosis, forming a soft cheesy mass the size of a pin’s head, and gradually enlarging to that of a pea, a bean, a hazel nut or larger. After a period of about 14 days the lymphatic gland nearest the seat of injection could be felt as a firm pea-like nodule, and in two weeks more a second gland on the line of the lymph circulation, had become enlarged and nodular, while the first, now the size of a large bean, had probably undergone distinct softening. This became adherent to the skin, burst and discharged continuously or at intervals with little or no tendency to heal. If killed at this date, the animal showed only the open sore and a chain of nodular pea-like caseated lymphatic glands leading up from it. The lungs might be apparently sound, but the spleen and liver usually showed miliary elevations on the surface, with clear grayish centers, as viewed under a magnifying glass, opaque patches were found on the omentum, and the lymphatic glands of the mesentery, of the portal fissures of the liver and of the Hilus of the spleen were distinctly enlarged and resistant. If not killed, the subject usually died 100 to 120 days after inoculation, and then the lungs were found studded with tubercles miliary or larger and more or less caseated; the bronchial mediastinal, subdorsal, pectoral, prepectoral, phrenic, mesenteric, hepatic, and splenic lymphatic glands were more or less enlarged and caseated, while the liver and spleen were enlarged and studded with multiple tubercles. Guinea pigs give the most 409extensive and intensive lesions, rabbits much less so, but in both emaciation and wasting are very marked. In short the lesions are essentially and unmistakably those of generalized tuberculosis.

“At first, however, incredulity prevailed and experiments on a large scale were inaugurated all over Europe and America to put the question to crucial test. Martin, Conheim, Burdon-Sanderson, Simon, Wilson, Fox, Lebert and Wyss, Fraënkel, Waldenbourg, and others inoculated with all sorts of non-tuberculous organic materials (bronchial mucus, foul pus, cancer juice, diseased liver, simple cotton setons, etc.) and from these in Guinea pigs there resulted local caseated foci, and implication of the adjacent lymphatic glands. It was found that the liquids from low types of pneumonia produced these apparently tubercular deposits, while that from acute sthenic pneumonia did not; that the cotton thread seton failed to produce the disease if it were first steeped in carbolic acid, and that the lesion caused by breaking a bone without injury to the skin failed to produce the characteristic lesions even in the very susceptible Guinea pig. It became evident, therefore, that the morbid results in these cases, were due to accidental inoculations with the poison of the tubercle, which is widely distributed, or with some pyæmic or other germs.

“Gradually the truth triumphed, and those who had at first been loudest in their opposition were led by their own experiments to become the firmest supporters of the new truth.

“As early as 1874, Gerlach had experimented largely in feeding the milk of tuberculous cows, and had infected calves, pigs, sheep and rabbits in this way. Chauveau in (1874), Klebs (1873), Semmer (1880) and Parrot (1870) fed calves, cats, Guinea pigs, pigs, sheep and a variety of other species of animals with tuberculous flesh or lungs, or saliva, producing tuberculosis in a large proportion of cases. In this manner they escaped the charge of the operation of a wound and of ærial bacteria, and yet succeeded in producing infection. The lesions in this case began in the intestinal mucous membranes and mesenteric glands.

“Another essay in the same direction was made by Tappeiner (1878), who infected rabbits, Guinea pigs and dogs, by enclosing them in boxes and compelling them to breathe tuberculous 410liquids intimately mixed with the air atomization. In these cases lesions began in the lungs and bronchial and mediastinal glands.^[1]”

Bacteriology. The bacillus tuberculosis, the essential cause of tubercle, was demonstrated by Koch in 1882. It was at first supposed to be peculiar in its indisposition and tardiness to take a stain, and in its retention of the stain once imparted, even when it is treated with acids. Later observations have shown that these characteristics are common to certain other bacilli, notably to those of leprosy, smegma, and to specimens found in timothy hay and other grasses, cow dung, milk and butter. These furnish sources of fallacy in the milk and butter especially, but when the specimens examined are taken from the interior of a tubercle, lymph gland or serous cavity the danger of error may be practically ignored. What is quite as important is the fact that the tubercle bacillus is subject to evolutionary changes in adapting itself to a habitat in different genera of animals, and to a lesser extent in different parts of the same animal, by which its pathogenesis is modified, but these variations do not materially affect the staining qualities. Still more striking variations have been found in old cultures, ovoid forms (Metchinkoff), club-shaped microbes and filaments (Metchinkoff, Klein, etc.), branching filaments (Fischl, Coppen Jones), divergent club-shaped groups, like actinomyces (Babes and Levaditi). The last named, seen in inoculated rabbits, have been held to establish a relationship between the microbes of tuberculosis and actinomycosis, as the club-shaped cells do not take the usual Ziehl-Neelsen stain for tubercle bacilli, but the Birsch-Hirshfeld’s actinomyces stain. Apart from the rabbit such variations are not likely to prove sources of fallacy in identification of the microbe.

Morphology. As met with in the tubercle of man or ox the bacillus is a minute rod with rounded ends, 1.5 to 3.5μ long, by 0.2μ in thickness. In the ox it is shorter and thicker on an average than in man. They are usually solitary, but two and exceptionally even three or four elements may be united. In stained specimens unstained portions are frequently seen (spores?). When cultivated on blood serum there is a tendency to form 411elongated rope-like colonies having a waving outline. Other evolution forms have been already noted.

Staining. The resistance to staining is overcome by a heated alkaline watery solution of methylene blue (Koch), or better by a carbolated solution of fuchsin (Ziehl-Neelsen). To a 5 per cent. watery solution of carbolic acid add one tenth of its volume of saturated alcoholic solution of fuchsin. The suspected sputum or scraping from a section of a lesion is spread in a thin layer on a cover glass by drawing over it the straight edge of a second cover glass, dried in the air, and passed three times through an alcohol flame with the smeared side up. It may then be floated on the surface of the staining fluid with the specimen side down, then gently heated for three or four minutes almost to ebulition, drying being prevented by the addition of more of the carbol-fuchsin solution as required. It is then washed in water to remove excess of the staining fluid and treated with a bleaching acid solution (sulphuric acid 5 per cent. or nitric acid 15 per cent.) When decolorized it is well rinsed in two or more portions of a 60 or 70 per cent. alcohol and then in water. Next stain with a 1 or 2 per cent. aqueous solution of methylene blue for one minute and wash off the excess with water. The tubercle bacilli will appear of a deep red and other bacteria blue.

Gabbett’s counter-staining and decolorizing solution is especially useful in economizing time. After staining, as above directed, in the carbol-fuchsin solution for one minute, wash in water, then cover with a solution of 2 grams methylene blue (powder) in 100cc. of 10 per cent. sulphuric acid, until the film has a faintly bluish tint: then wash thoroughly in water and examine. Tubercle bacilli come out red, others blue.

In examination of tissues the microscopic sections are steeped for twenty-four hours in the carbol-fuchsin solution (or 1 hour at a temperature of 45° to 50° C.), then decolorized in a 5 per cent. sulphuric acid for a few seconds, then in a 70 per cent. alcohol: they are then counter-stained in an aqueous solution of methylene blue, washed in water dehydrated with absolute alcohol, cleared up in xyol or oil of cedar, and mounted in Canada balsam.

Biology. The bacillus tuberculosis is notorious for its variant forms, assumed in adapting itself to given environments, and which it retains with considerable tenacity for a time, even when 412placed in a new and different medium. It is largely held to be an obligatory parasite, and incapable of survival as a saprophyte, yet Straus, Nocard and others, have shown that the form obtained from the tuberculosis of birds can easily be made to live in suitable dead mixtures of organic matter. It is also notorious that the bacillus taken direct from the tubercle of the mammal, and which, as a rule, fails to grow at once in glycerined bouillon, yet, after a first successful culture in the new medium, often adapts itself completely, and thereafter it can in many cases be transferred from bouillon to bouillon, with as great certainty as it could formerly be inoculated from ox to ox. The difference is one of habit and adaptability, rather than any primary and permanent distinction of species. There is every reason to believe that the microbe has lived, and under given conditions can still be made to live as a saprophyte, with a greatly reduced adaptability to parasitic life in the animal, just as we see to-day that it is only with great difficulty transferred from certain genera of animals to certain other genera (from bird to ox and vice versa). Trudeau tells us of a culture of a bacillus tuberculosis from man, inoculated on the rabbit and then cultivated in vitro in successive generations for six years, that was in this way robbed of its pathogenesis for Guinea pigs, which, after inoculation, lived for many months, some two and a half years, and some even recovered. The average duration of life in the Guinea pig, after tuberculosis inoculation from man, rabbit, Guinea pig or recent culture is but seventeen days. The bacillus of human sputum often produces only localized tuberculosis in the ox. Even in the same species and individual the pathogenesis often varies materially. Nothing is more familiar than the slow progress of tuberculosis in the bones and lymph glands of man, on the one hand, and its frequently rapid progress in the lungs, liver and brain, on the other. As inoculated on the lower animals bacilli from the lungs of man are usually more virulent than those from the lymph glands (Creighton, Arloing, F. Craven Moore, Courmont and Denis). Among seven specimens of human sputum, the bacilli in six cases showed a fair average vitality, whereas those of the seventh failed to grow on blood serum of the dog (Theobald Smith). In both man and cow a large proportion of cases of tuberculosis remain localized, the 413disease lasting for years with little or no appreciable advancement, and not a few subjects appear to make a permanent recovery.

On every hand this evolutionary tendency of the bacillus tuberculosis places itself in evidence, demanding a recognition of the fact, that more or less transient or lasting variations in accordance with previous or existing environment, control to a large extent the transmissibility of the disease among different genera and even among individuals of the same genera and species, and also the fatal progress, or the mild and evanescent issue of the infection.

Even the most widely divergent of these evolutionary forms can often be made to approach each other and apparently merge into one type. Profiting by the example of Metchnikoff, Nocard enclosed in collodion capsules the bacilli of the human sputum and inserted the capsules into the peritoneal cavity of chickens which had proved refractory to their direct inoculation. This excluded the direct action of the leucocytes from the encapsuled bacilli, but allowed the endosmosis of the serum of the fowl for their nourishment. After a sojourn of four months or more they were transferred to other capsules and again enclosed in the peritoneum and after a second and third transference of this kind it was found that the bacillus had become actively pathogenic for the chicken, having acquired the infecting potencies of the bacillus of avian tuberculosis.

In keeping with the above is the fact that both rabbit and horse are easily infected by the bacillus obtained from birds, and that after a certain number of transmissions through the rabbit the issue of the bacilli of bird and mammal appear to become identical. No less instructive are the cases of the infection of carp by human sputa and the conveyance of tuberculosis to rabbits and Guinea pigs by inoculation with the nodules of the infected carp.

The vitality of bacillus tuberculosis is strong but variable. In sterilized water at 46° to 64° F. the human bacillus survived for fifty to seventy days (Chantemesse and Vidal), the bovine indefinitely (Galtier) and the avian bacillus at a higher temperature one hundred and seventeen days (Straus and DeBarry). In dried expectoration the bacillus of man still infects after nine or ten months (Koch, Schill, Fischer, De Thoma). In infected cow’s lung, dried and pulverized, it infected Guinea pigs at 102 days (Cadeac and Malet). In putrid matter it infected after 43 414days (Schill, Fischer), 167 days (Cadeac and Malet), several years in a grave (Schottelius).

It is not destroyed by gastric juice (Fischer, Falk). The bacillus from tubercle of birds has a much greater vitality than that of mammals. Marfucci successfully seeded new media from a culture of two years old, and cultures in artificial media can be started more successfully.

Full sunlight renders sputum on a solid nonabsorbent surface noninfecting in several hours, varying according to the thickness of the layer (Koch, Straus). When sputum is mixed in soil it may survive until the 137th day (Feltz). On woolen cloth it may live five hours (Migneco).

Diffuse daylight, with shading from the sun, killed in seven days (Koch), to eighteen days (Lucibelli).

X-Rays do not arrest the growth of cultures (Blaikie, Pott, Ausset).

A dry temperature of 212° F. for an hour left some of the bacilli still infecting to Guinea pigs (Lartigan).

A moist heat of 140° F. for one hour sterilizes (De Man, Th. Smith, etc.). The scum formed on the milk may still prove infecting (Th. Smith). Half an hour of a moist temperature of 212° F. is sterilizing. Yet in the case of steaks, roasts and boiled meats the size of the piece often prevents the reaching of this temperature throughout, and it becomes unsafe to use any meat in which the redness of the juice shows, that the albumen has not all been fully coagulated (162° F.).

A freezing temperature, −16° to −26° F., does not devitalize the bacilli, even when alternated with thawing at intervals for several weeks (Galtier, Cadeac and Malet).

Heavy salting of meats has been thought to kill the bacillus in a month. After 15 days in salt the microbe failed to kill rabbits, but still killed the Guinea pig, whereas after 30 days it killed neither (Galtier). The fact that salted meats are always unequally impregnated in different parts, renders this extremely unreliable and more of a snare than a guide.

The action of chemical disinfectants varies not only with the agent but also with the medium in which the bacillus is found. In simple liquid media (bouillon) the following results were obtained:

415

Parts per 1000. Killed in.

Carbolic Acid 50:1000 30″ (Yersin)

„ „ 10:1000 1′ „

Alcohol (absolute) 1000:1000 5′ „

Ether 1000:1000 10′ „

Iodoform ether 10:1000 5′ „

Mercuric chloride 1:1000 10′ „

Salicylic acid 2.5:1000 6 hrs. „

Anilin water Saturated

Thymol 3:1000 3 hrs. (Yersin)

Formalin vapor 60:1000 40 hrs. (Murray)

Sulphurous Acid (Sulphur 1 oz. to cubic metre) 14 hrs. (Vallin).

The following agents proved ineffective: Saturated aqueous solution of creosote, or of B-naphthol, of naphthalin, of potassium iodide, of potassium bromide:—bromine water, iodine water (1:500), iodoform solution or vapor, vapor of oil of turpentine.

ACCESSORY CAUSES OF TUBERCULOSIS IN ANIMALS.

While recognizing that in the absence of the tubercle bacillus there can be no tuberculosis yet we must not ignore the fact that many conditions of the animal system and its environment contribute largely to the propagation of the disease on the one hand, or to hinder its progress on the other. None of these conditions can call the germ into being de novo, but in its presence, they greatly favor its diffusion or even its malignancy. Like any other seed, this bacillus requires a suitable soil and favorable climate, to bring out its most destructive development. In striking the balance, we have to guard against the error of so many, who would attribute to the germ alone the deadly results and who assume that these should be the same under all conditions, and the opposite error no less prevalent, that ascribes the evil to the conditions, and holds that without these the germ would be harmless.

Hereditary Predisposition. Racial Vulnerability. Before the discovery of the specific bacillus, when as yet tuberculosis was held to result from a constitutional weakness, or cachexia in which deterioration of cells was held to be the main factor, the disease was held to be mainly hereditary, and its every day transmission in the line of descent, and the increasing mortality to extinction of given families were confidently appealed to in support of the 416doctrine. Now, however, we recognize that congenital tuberculosis in man or beast is very exceptional, and that the morbid process almost invariably takes its start from the germ implanted after birth. In Saxony when the tuberculous cows were 16.5 per cent. tuberculous calves were but .2 per cent., though the latter had been fattened on the milk of the former. In Munich but two calves were found tuberculous in 400,000 killed, and in Lyons but five in a similar number. Up to the present the number of calves recorded as tuberculous at birth does not exceed seventy.

That the young almost always contracted the disease, only after birth, virtually disposes of the alleged heredity of the tuberculosis but it by no means antagonizes the heredity of the racial vulnerability. As man, cattle, swine and Guinea pigs show a much greater vulnerability than the carnivora in general, so certain families in each of these genera show a more decided susceptibility to tuberculosis under similar conditions than do certain other families. This goes far to explain the appearance of tuberculosis, in certain lines of blood, and its advance to the extinction of the family, while under no better environment, other families can count on a practical immunity. In the Burden herd of Jerseys in 1877, I condemned eleven animals, verifying my diagnosis by necropsies, and found to my surprise that I had taken every representative, even the grades, of a given family, and left all the pure bred members of a second family untouched. Both families had mingled freely in the pastures and yards, yet the second family furnished no cases of tuberculosis then nor for many years afterward. The case is all the more striking that the non-tuberculous family gave the largest yield of milk and might have been expected to run down rather than the other on account of this drain.

Close Buildings. Lack of Ventilation. Air rendered impure by being breathed again and again, predisposes strongly to tuberculosis, and has been even looked upon as the sole cause (Macormac). Everywhere city dairy cows, kept in confined, close buildings, suffer severely (6 to 20 per cent. and upward); in Berlin 75 per cent. (Ostertag); in Denmark 61 per cent. (Bang), while in the same districts country cows are comparatively immune (often 1 to 2 per cent.), and steers raised in the open air still less (0.02 per cent. for our Plains cattle). For the slighter 417cases of tuberculosis in man and beast, life in a pure open air, day and night, in a genial climate, gives the best hope of improvement or recovery. In the Burden Jersey herd above referred to, animals condemned in spring as tuberculous, were turned out to pasture during the summer where they maintained an appearance of robust health, yet when returned to the barns in fall they fell off rapidly, so that some had to be helped to rise in the stall. “The stabled cow, the tame rabbit, the monkey, the caged lion, tiger or elephant are almost invariably cut off by scrofulous affection” (Aitken). It has long been noticed that sailors sleeping in close spaces (Bryson, Parkes), soldiers confined to close stone barracks even in the tropics (Parkes), suffer much more than the officers in more spacious rooms (Clark). Monks and nuns (two-thirds of the deaths, Leudet) occupying confined cells, and the inmates of prisons (four times the average outside, Baer) have shown an extraordinary prevalence of tuberculosis and attendant mortality. While this can be attributed mainly to the preservation and concentration of the bacillus in such places, a considerable allowance must be made for the impure and rebreathed air.

Dark, Foul, Damp Stables. Dark stables are usually close, dirty and damp as well, and all these conditions alike conduce to tuberculosis. Darkness hinders the development of organic coloring matter in living bodies, whether chlorophyll in plants or hæmoglobin in the blood of animals. Hæmoglobin is the main oxygen carrier in the blood, and in case of its deficiency the tissues are not properly ærated. The result is as if the inhaled air contained little oxygen, so that darkness further intensifies the evil of rebreathed, deoxygenated air. The extraordinary mortality from tubercle among prisoners, monks, nuns and miners serves to further accentuate this conclusion.

Trudeau’s experiment with rabbits is instructive in this connection. Of a number inoculated with the same number of tubercle bacilli, one half were kept in the open air and the rest in a dark, damp, underground place deprived of sunlight. When killed on the same day, it was found that the open air rabbits showed only slight lesions or none, while the underground lot had extensive tuberculosis.

418The impure stable air lowers the vital tone of the animal, especially if the impurity has come from animal exhalations.

The same is true of damp air, “a damp ship is an unhealthy one,” and Bowditch and Buchanan pointed out the especial prevalence of tubercle in cold, damp, undrained, foggy localities. This does not hold for all damp lands, yet damp, fog, and cold are especially hurtful in presence of the germ.

INSUFFICIENT OR UNWHOLESOME FOOD.

Starvation and indigestible or innutritious food contribute to debility, and lessen the power of resistance. Hence in the poor, half starved denizens of city slums, and among neglected herds of cattle, tuberculosis, once introduced, makes rapid and extensive ravages. Conversely overfeeding often acts in the same way, developing indigestion and thereby robbing the tissues of their proper nourishment.

HEAVY MILKING.

In dairy cows, of milking breeds, the drain on the system is liable to prove too great, under a ration-for-milk, warm sloppy mashes of grains, bran, middlings, roots, distillery swill, exclusive diet of silage, saccharine roots, or marc, warm drinking water, a warm atmosphere, liberal salting, and enforced idleness in the stall, with careful stripping of the bag. The butter cows, (Jerseys, Guernseys, Alderneys, etc.) are especially liable to suffer, as the greater the yield the more the system is robbed of the adipose material which is so needful to a vigorous health. When the cow has been reduced to a high-pressure milk factory her physical size reduced to obviate the need of a large sustaining ration, and her milking capacity stimulated to the highest degree, the presence of the tubercle bacillus is especially dangerous.

CONFORMATION.

It was formerly held that cows with heads narrow between the horns, small thin necks, narrow chests defective also in depth and length, loose projecting shoulders and elbows, pendent, pot bellies, with hollow flanks, and a general laxity of the frame were 419especially predisposed to tubercle. In many such cases the suspected animal was already the victim of the affection, which had brought out these characteristic features of weakness and emaciation. In other cases the unthrifty appearance was due to poor feeding and care or to chronic disease, which in robbing the system of vigor and hardihood laid it open to the attack of the tubercle bacillus whenever it was introduced. Even when there was no such depressing influence affecting the individual, the inheritance of such a frame, betokened a constitution lacking in vigor, and with little power of resistance to the invading microbe. Some milking breeds which tend to the above conformation, show an unusual development of the lymph glands and plexuses, and as tuberculosis attacks the lymphatic system preëminently, the bacillus finds an especially favorable field for development in such systems. It would, however, be an error to assume that the compact, rounded frame, with circular chest and abdomen, and full, firm neck and shoulders, with a great disposition to fat and little to milk, is in any degree immune. Under the presence of the tubercle bacillus, and close stabling, they often succumb quite as rapidly as the most susceptible milking breeds. The meat producing breeds with a strong propensity to fatten, have an extraordinary development of lymph spaces and plexus in the intermuscular and subcutaneous connective tissue, and the microbe finds a welcome home in their sluggish, inactive and atonic systems as well as in the typical dairy cows.

BREEDING TOO YOUNG.

Breeding from immature animals undermines the vitality as the system is overtaxed to sustain at once the demands for further growth, for the nourishment of the unborn offspring, and for the yield of milk. Some families of Jerseys have been undoubtedly injured in this way, through the desire to diminish the size of the cow, and yet retain the highest milk and butter yield.

CLOSE BREEDING.

Inbred families are proverbially subject to tuberculosis. By pairing individuals that show in a marked degree the desired qualities of early maturity, heavy milking, or fattening, the 420greatest stimulus is given to the enhancement of such qualities, and with this there is the correspondingly ready receptiveness to the tubercle bacillus. To this is added a degree of constitutional delicacy which comes from too close breeding, and which otherwise shows itself in an encreasing infertility, when bred with an animal that is nearly related. In addition, the high bred animal is kept much indoors, where the bacillus, once introduced, is easily preserved and propagated, and is denied the free outdoor life and exercise which might develop muscle and vigor. This is no valid argument for introducing inferior blood to the deterioration of the economic value of a race, but rather for the complete exclusion of the bacillus which may find in our treasured herd an especially inviting field for its ravages.

AGE.

In both man and beast, age appears to have a predisposing effect, but apart from debility or trauma, this may be fully explained on the ground of often repeated infection, an indoor life, and, in dairy cows, the excessive drain upon the system. In thoroughbred herds of cattle, in which the cows are preserved as long as they will breed, and in dairies where they are kept as long as the milk yield is satisfactory, the oldest show by far the largest percentage tuberculous. In secluded individual dairies we have found 100 per cent. affected, Ostertag gives the average for Berlin at 75 per cent., and Bang for Denmark at 69 per cent.

PREDISPONENT DISEASES.

As already noted all diseases which undermine the health tend to diminish the powers of resistance to the tubercle bacillus. To be especially dreaded, are long standing diseases which produce emaciation and debility, fevers that for a length of time impair sanguification, metabolism and nutrition, diseases of the digestive organs which cut off the requisite supply of nutritive material, and, above all, diseases of the lungs and air passages that impair the tone of the tissues and invite the attack of the invading microbe. Bronchitis, laryngitis, pharyngitis and tonsilitis in all their varied forms are to be particularly noted. Even in man it is believed that one of the most common channels of infection entrance is through the open tonsillar crypts, and the same doubtless 421is true of animals. Pigs, with their large tonsils and frequent infection through feeding, are probable examples of this, and when, in addition to the detention of the microbe in the cavities, there is an inflammation and debility of the tissues, the opportunity for infection is greatly enhanced.

ENCREASED TRAFFIC IN (TUBERCULOUS) ANIMALS. DAIRY EXTENSION.

In common with all infectious diseases, tuberculosis owes its great extensions to the sale and purchase of animals. Where an indigenous race of cattle is raised and sold, without any additions from without, tuberculosis is usually rare and confined to the one herd, or to those having intimate intercommunication with it. Where, on the other hand, a large stock is kept up, as in milk dairies, and few or no calves are raised, but the bulk of the cows are sold off yearly and replaced by new purchases, tuberculosis, sooner or later, finds admittance through the body of an infected animal, and once implanted in the herd, it goes on encreasing, without limitation, except by the sale or death of the more seriously affected. The larger the herd and the greater the number of yearly changes, the greater the number of opportunities for the introduction of an infecting animal. Where a great part of the herd is turned off yearly, and the new animals are drawn from any or every source indiscriminately, it would border on the miraculous if such a herd were to remain free from the infection for any great length of time. The recent extension of tuberculosis in herds has been coincident with the great development of commerce in live stock, and the rapid transit on land and water by steam. Before the days of the steam engine, animal plagues advanced slowly and uncertainly, excepting in the presence of a great European war, which drew animals from all available sources, congregating them in large mutually infecting droves in commisariat parks, and marching them in the wake of the army for its daily supply. Inevitably every country invaded was infected, and the plagues spread from the line of march in all directions. The more deadly plagues, like rinderpest and lung plague, were the first to appear, and in this lay a certain measure of palliation of the evil, as the exposed and often weaker animals were killed off, so that the slower contagion like that of 422tuberculosis had not time to develop. This mitigating influence held good so long as the deadly plagues were not placed under effective control. When, however, a nation successfully extirpated and excluded lung plague and rinderpest, the way was opened for a freer extension of tardily developing plagues like tuberculosis. The great development of beet sugar factories and the accumulation of herds to consume the marc; the extraordinary extension of manufactures which have made England and certain countries of Western Europe consuming rather than agricultural lands, and the wonderful modern expansion of dairy husbandry have combined to encrease and concentrate the cattle industry in ratio with the manufacturing and commercial progress of the nations, and as the live stock are kept under a milk-stimulating regimen and a life passed largely indoors, the way has been open for an ever-advancing encrease of tuberculosis. In the United States the centralization of population in the Eastern States and in all great centres of industry and the concentration of cows for the milk supply, and in certain districts in connection with butter and cheese factories, have contributed to wide local extensions of consumption. Hence it has been no uncommon thing to find herds in the vicinity of cities with 20 to 100 per cent. affected, in striking contrast with the 0.02 per cent. found in the fat cattle from the plains.

The modern railway traffic brings to all these swarming centres of animal industry, live cattle from long distances to supply the constant depletion through deaths and the disposal of dry cows, and thus the whole Atlantic slope is drawn upon to fill the eastern stalls. Infected animals thus shipped from Ohio, Indiana, Illinois, Wisconsin and Michigan for the good of the herds in those states find new homes in New York, or New England, where they have four to twelve mouths to propagate the infection before they are themselves disposed of. As in the days of the lung plague in America, the eastward trend of bovine traffic, becomes to a certain extent a protection and benefit to the herds of the west, but in equal ratio it operates to the detriment of our eastern stock. What is true of the planting of new centres of infection in the busy dairy districts of the east, and of the steady increase of disease in already infected herds, through the constant addition of new cases purchased, is no less true of the corresponding 423districts devoted to dairying interests in the west. It is the natural order of things, that, everywhere, the new accessions of infection, coming in the lines of trade, into large dairy herds, kept to a great extent indoors for months at a time, must hasten the general infection of such herds. When, therefore, no intelligent measures are interposed to check the evil, we must expect that the marked increase in the prevalence of tuberculosis, which we have witnessed of late years, shall become more and more evident year by year. Journals have claimed credit for befriending the stockman, in opposing all control of the cattle traffic, dealers have denounced all control as ruinously oppressive and injurious, and legislators have turned a deaf ear to the warnings of science and experience, but time, in this as in all other plagues, will justify the demand for an intelligent control, and the increasing losses will one day open the eyes of the stockowners to the fact that their truest friends are those that would exclude the baneful seed, and kill it ere it has had time to germinate and bring forth its ever increasing harvests.

In the absence of any systematic and efficient government protection in this line, the stock owner can only protect his sound herd by the rigid exclusion of all animals that are not of his own breeding, or in case of purchase, by an exhaustive inquiry as to the occurrence of sickness or deaths in the herd from which he buys, and by the professional examination and test of every animal to be bought. Even then he must promptly separate, test, and, if necessary destroy any animal that proves unthrifty, or which by cough, diarrhœa, wheezing or other sign gives evidence of probable tuberculosis.

Unregulated Traffic in Tuberculous Animals from Other States. The danger of buying animals untested is in no degree lessened when they are sent in from other states. While some make a business of supplying the store market with what they believe to be good stock, there is always the temptation to turn off animals that are unthrifty or poor milkers and which have proved less profitable than the others. Some even have the herd tested and sell off those that show evidence of tuberculosis. Unless, therefore, it is held in check by the tuberculin test, the traffic is made to the extent of such sales a direct means of disseminating tuberculosis.

424

ASSORTING THE TUBERCULOUS ANIMALS FOR SALE IN A GIVEN STATE.

A still more injurious result comes from the order of given States, that the admission of store cattle shall be guarded by the tuberculin test of each animal, and the supineness or worse, of adjacent states in establishing no effective safe guard against the disposal of the tuberculous culls in the unprotected State. Cattle from the west or elsewhere in the United States, arrive in a great public market as, for example, New York, they are here tested, those that stand the test are shipped into one of the States requiring the test (Massachusetts, Pennsylvania, New Jersey, Canada), and those that have shown the reaction of tuberculosis are sold into the herds of the State in which they were tested. The most malicious enemy of the New York stock owners, could not devise a surer means of stocking the herds of the State with tuberculosis than this atrocious system. Yet when the present writer had a bill introduced into the legislature to correct the evil the opposing interest proved strong enough to prevent it from coming to a vote. The legislative committee on tuberculosis which sat later, and upon whose attention the subject was pressed, also practically ignored it and the statute which this commission inspired leaves the matter as bad as before. Under the present law the New York purchaser must secure his own interests by having every animal he buys tested by a trustworthy veterinarian.

Sale of Sound Animals Concentrates the Tuberculosis. The action of one or more States in admitting store cattle only after a tuberculin test, acts directly in encreasing the relative number of tuberculous animals in adjacent States. The purchaser from Pennsylvania for instance, goes into a New York herd and purchases all the best animals on the condition that they pass the tuberculin test uncondemned. It follows that the New York herd is left with the tuberculous cattle only, and those that, aside from tuberculosis, are of low value or profitless to keep. Further as the advance of tuberculosis is proportionate to the relative number of tuberculous subjects in the herd or building, and the concentration of the poison, the depreciated herd is almost certain to become rapidly and generally affected by the disease.

The Denial of Indemnity for Tuberculous Animals Killed. Several American States (and notoriously New York in the 425recently enacted statute) forbid compensation to the owner for any animal killed because it is affected with a contagious disease, and to prevent the extension of such contagion. All history attests, and any consideration of human nature might teach, that such a measure is only calculated to spread the infection. The owner of an animal, affected with a contagious disease, who can get little salvage by turning it into beef, and none at all if he hands it over to the State for slaughter, will naturally think of putting it on the market, where he can secure a good price. How much more is he tempted to do this when the disease is an occult one, and the animal shows the outward appearance of health, as is the case in nine-tenths of many tuberculous herds! Crime cannot be fixed on the seller, for he is not an expert, and cannot be expected to diagnose the disease. If the infected cow is of little value for the dairy, she is passed on, from hand to hand, leaving infection in every herd she has entered. The ultimate owner (in whose hands the State finds her and diagnoses her disease), though he may have bought her in good faith as a sound animal and paid a correspondingly high market price, is made to lose the whole value of the cow. The real offender who knew her to be a tuberculous animal, and sold her in consequence at the price of a sound cow is shrewd enough to keep himself out of the clutches of the law, while the honest purchaser who has been already swindled, has his income and property cut off without compensation. Such a law is self-evidently unjust; it plays into the hands of the swindler at the expense of the just man; with the object of protecting the community against infection, it refuses to call on the public for any contribution toward its own protection. The system is a direct bid for extensive and encreasing violation of the law and diffusion of the infection and must be accorded a prominent place in the list of causes. It would be surprising to find that any country ever extirpated an animal plague by working on such a system. As a matter of fact no country ever did; all such sanitary successes from the extinction of sheeppox or rinderpest in Western Europe, to the recent stamping out of lung plague in the United States, were based on a just compensation to the owners of the stock. When, therefore, veterinary sanitary principles and experience have been so far ignored as to allow the passage of a law, which at once favors the diffusion of infection 426by the crafty sale of the infected, the expatriation of the healthy animals from the home herds, leaving only the diseased, and finally the selection from herds in transit of the tuberculous ones to be scattered widely among the herds of the State, we must not wonder at the continuance or encrease of tuberculosis in the commonwealth. Until a more rational and common sense legislation can be secured, the unfortunate stock owner must defend himself by the expensive alternative of testing every animal he buys.

Private Testing of Herds and Sale of the Tuberculous. A most reprehensible practice is the private testing of herds and the sale as store animals of those that react. In this way a herd may be cleared of infection, but at tenfold expense to the public at large, as every animal sold may convey the infection into a separate herd. It is, however, a natural outcome of the unwise system of refusing indemnity for the infected.

Habituating to Tuberculin Testing and then Selling under Test. Many (not all) cattle, when injected with tuberculin repeatedly at short intervals, acquire a tolerance of the agent and fail to react as at the first test. We have in such cases examined the animals post mortem and found active tuberculosis. Unscrupulous owners, aware of the fact, have their diseased cattle injected repeatedly every few weeks, and as soon as they fail to respond, sell them under the guarantee of the tuberculin test. The cattle, of course, carry the infection into other herds. This swindle could be obviated if it could be made a misdemeanor to have or use tuberculin except as a State or Federal official acting for the government. This would imply the corollary that the State should test the herds when called upon.

Antipyretics During Tuberculin Test. Another method of undoing the tuberculin test is to feed large doses of antithermic agents to depress the temperature at the time the rise from tuberculin would take place. Tuberculous cattle may thus be sold as sound animals, with a certificate of having successfully passed the tuberculin test, the operator having given such certificate in perfect good faith. It suggests the importance of withholding tuberculin from public use, or of securing an absolute control of the feeding and watering of the animals during the test.

False Certificates of Tuberculin Tests. Stock owners have reported to the writer alleged tuberculin tests of their herds which 427were completed in three hours, and others have named instances of marking animals for shipment and giving certificates of testing where no tuberculin had been used and no examination beyond the most cursory glance had been made. This might be expected of some non-graduates, registered on a basis of alleged practice, shamefully ignorant of veterinary medicine and conscious of their false position, and some educated veterinarians thus placed at a disadvantage may have been tempted to follow suit, but it can only end in personal disgrace and an inevitable extension of tuberculosis. Begotten in a legislative wrong and nourished by moral weakness, it can only grow into greater evil. Unfortunately such unworthy actions throw discredit on the very name of sanitary police. To avoid the evil every one aspiring to the responsible work of testing cattle should be thoroughly examined as to fitness and licensed to practice under a heavy penalty for neglect or malpractice.

Feeding Hogs on Fresh Offal from Abattoirs. It has been a common practice, especially in country districts, to turn the raw offal of slaughterhouses to pigs, and as the tubercle is usually concentrated in internal organs, the hogs become infected in large numbers. In public institutions which slaughtered their own meat I have found the hogs all but universally tuberculous. The danger is only slightly lessened when the hogs are fed raw butcher and kitchen scraps in swill. It suggests the compulsory boiling of all swill or garbage containing raw meat.

Feeding Calves and Hogs on infected Milk. Though it has been repeatedly shown that the majority of moderately tuberculous cows do not yield infected milk, yet in every tuberculous herd, at irregular intervals, one or more are attacked with tuberculosis of the mammæ, and the drinkers of the milk take in the tubercle bacilli. This will happen in the most strictly supervised tuberculous herds, while in those that are less carefully managed, the milk that is considered unfit for human consumption is fed to pigs or calves. In one dairy, I found that the calves, all fed in this way afterward reacted under the tuberculin test, while the following year the crop of calves, though fed on the milk of the same diseased cows, with this difference that the milk had been first heated to 180° F., without exception grew up healthy, and not one reacted under the tuberculin test.

428Feeding hogs after Tuberculous Cattle. Where cattle and hogs are kept on the same place, it is a common practice to let the swine clean up all food left by the satiated cattle. If there are tuberculous cattle, affected either in the air passages or alimentary tract, the pigs become infected by taking in the expectoration by which the food is soiled, or by rooting around where the cow manure has fallen.

Feeding from a Common Trough. In an infected herd, a common cause of extension is found in the use by the whole herd of a common feeding trough, in which the food soiled by virulent discharges, is taken by healthy animals. The habit of tying a cow in different stalls in succession as she happens to strike one, in place of keeping each cow by its own stall is a fruitful source of infection. Even when each cow is kept by its own stall, she often becomes infected by reaching into the feeding trough in front of the next cow on the left or right and taking in soiled and infected fodder. In swill stables the evil reaches its maximum, as the feeding trough for 50 or 60 animals is slightly inclined so that the liquid food runs from the supply end to the other, and infecting expectorations are carried in front of all in turn.

Dry, Dusty Stables. Tubercle bacilli are not carried out on the expired air, unless there is forced expulsion as in coughing, snorting or sniffing. In such cases the solid particles are thrown off in masses or fine spray and lodged on surrounding objects. These, together with infecting discharges from bowels, urinary or generative organs, open sores, etc., dry up, and rise on the dust, and, as sterilization occurs slowly indoors, they cause more or less infection of the animal inmates. Cornet, Tappenier and others have thoroughly established this as a common form of transmission, and shown the great importance of cleanliness, disinfection and the removal of infecting materials without raising dust. In an establishment in Paris, a consumptive had served for 3 years. In the following 10 years, 15 of the 20 employés died of phthisis.

Extension through Vermin. As rats and mice (and other rodents) are susceptible to tuberculosis by ingestion (Galtier) it follows that they may become the media for extension of the infection through fodder in which their droppings are scattered, 429or from their feeding in the same troughs as the cattle or swine. For swine in particular the danger is greater because of their carnivorous habits; the rat acquires tuberculosis through eating the offal of the abattoir, or the scraps of the butcher’s stall, or kitchen, and the sick rat is thereafter easily caught and devoured by the pig to its own undoing. To block this channel of infection the destruction of vermin about slaughter houses, stables and pig pens is a most important consideration.

Flies and Other Insects as Carriers of Tuberculosis. These congregating on tubercular sores, around the nares or lips, on the skin contaminated by the virulent bowel discharges, on dishes holding infecting milk, on objects soiled by infecting discharges, on diseased carcasses at abattoirs, rendering works and elsewhere, (Spillman, Hoffmann, Lartigan, etc.,) and on graves where the earth worms have brought the bacillus to the surface, (Lortet, etc.) become more or less active agents in disseminating the virus. In this way food and water are contaminated, and exceptionally, infection may even be implanted on sores. As the excreta of the flies contain the virulent bacilli, the latter are deposited on windows, walls, furniture, etc., and may be later disseminated in the dust of the apartment.

Dewevre found tubercle bacilli in the bedbugs infesting a bed in which successive cases of consumption had developed, showing that other parasitic or rapacious insects besides flies must be looked on as possible propagators of the bacilli. There is reason to suspect, lice, fleas, ticks and acari especially. The same is true of leeches and other rapacious invertebrates.

LESIONS. THE TUBERCLE.

The characteristic lesion in tuberculosis is the tubercle, taking its name from the small rounded nodule which, at first virtually invisible, encreases often to the size of a millet seed, or a pinhead or even larger, and which by confluence with others, forms conglomerate masses of all sizes to which the term tubercle is still applied. Where the bacillus tuberculosis is implanted, the fixed tissue cells are stimulated to an undue proliferation, and a diapedesis of leucocytes takes place from the neighboring capillary blood vessels, the whole eventuating in the formation of a rounded cluster or nest of epithelioid and giant and later small rounded 430lymphoid cells in a fine fibrous stroma. Baumgarten and his followers claim that the larger epithelioid and giant cells result from the karyokinesis and proliferation of the fixed tissue cells, epithelial and endothelial cells, and that the lymphoid cells which later (often after the eighth day in experimental cases) invade the lesions, are alone the product of the migrating leucocytes. Metchnikoff, Yersin and others contend, on the other hand, that epithelioid and giant cells are directly derived from the leucocytes and endothelial cells and like these are possessed of actively phagocytic qualities. As the final outcome before caseous degeneration, is the great predominance of the small lymphoid cell, it may well be questioned whether this is not the result of active encrease in both kinds of cells, as appears to happen in many other inflammations. For our present purpose it is well to note the early characters: Centrally often a large (giant) cell with a number of peripheral nuclei and at times, branching processes; around this as a second zone epithelioid cells of large size, with round or oval nuclei, and sometimes giant cells; outside this a third zone of small rounded lymphoid cells with large nuclei. There is a delicate fibrous network between the cells, but no indication of capillary blood vessels, the absence of which may partly explain the constant tendency to degeneration, necrosis, and caseation. The tissue around the miliary tubercle is red and congested.

Caseation. A striking characteristic of tubercle is the occurrence of coagulation necrosis, beginning in the centre of the specific nodule as a whitish or pale softening and degeneration of the cell elements and gradually extending toward the circumference. The cells, and even the proximate tissue elements, die and disintegrate passing into a structureless, granular or hyaline debris, which has been named from its supposed resemblance to old, ripe, soft cheese. Baumgarten has observed that the small lymphoid cells are the first to degenerate, followed by the epithelioid and giant ones.

While the formation of tubercle is at first a productive inflammation of which the cell clusters and nodules are the result, yet the tendency to necrosis, and caseation is so great that it must be looked upon as one of its most prominent features, and is rarely absent, whether the lesion exists in the connective tissue of the 431lungs, liver or other organ, in the lymph glands, in the respiratory or intestinal mucosa or submucosa, in the osseous cancelli, brain or skin. It is, therefore, largely pathognomonic, yet it is not peculiar to tubercle, being common in glanders, and other infective inflammations. Its presence should always lead to a search for the primary tubercle nodule, with its nonvascular cluster of lymphoid and giant cells and above all for the specific bacillus resistant to staining.

The tendency to extensive degeneration and caseation is especially marked in swine, in which the resulting debris is often so liquid that the tubercles bear a strong resemblance to abscesses.

Calcification. The deposition of lime salts (mainly phosphates) in the tubercle is a common feature of advanced cases in man and pig, but especially in cattle. It is unknown in rabbits and Guinea pigs. The tubercle assumes a hard cretaceous aspect and feeling, grates under the knife and crepitates when pressed. This is always an evidence of chronicity, but it has been observed in swine in 3½ months.

Fibroid Degeneration. Fibrosis. In this case a productive fibroid inflammation takes place in the tissue of the tubercle, and it is resolved more or less extensively into a hard, white, resistant body. This is the pearly mass which has given rise to the name of the pearl disease (perl-zucht) in Germany. It may be fibrous throughout, but usually a number of the nodules show a caseated centre while the external zone, that nearest to healthy tissue, has alone taken on the conservative fibroid development. Like cretifaction, fibrosis is an indication of chronicity in the lesion. It is often seen in man, but still more so in cattle, in which it affects particularly the abdominal cavity, but also to a lesser extent the chest and other parts. It is remarkable for the paucity of bacilli to be found in its substance, often requiring many sections and infinite patience to reveal the presence of the microbe. This comparative lack of actively multiplying bacilli is doubtless one factor, operating in the direction of conservative processes, chronicity and even partial recovery. In experimental tuberculosis the extent and rapidity of development of tubercle, as also of the degeneration are found to be closely allied to the number of bacilli introduced.

Cattle: Pulmonary Tuberculosis. One of the most frequent 432seats of tuberculosis, the lung, may in acute cases show a diffuse miliary tuberculosis, a considerable part of a lobe or of several lobes being congested, infiltrated, and filled with small individual tubercles, grayish or transparent in the midst of the general redness. A second form, often of old standing, is in the shape of hard masses, often circumscribed or isolated, and easily felt when the soft lung tissue is manipulated. They are respectively formed by the local aggregation, and confluence of the small miliary nodules and may vary in size from a pea to a mass of ten or twelve inches in diameter. On section the miliary tubercle may not yet show central caseation, but the larger ones do so as a rule. The caseated nucleus may be soft, cheesy and somewhat homogeneous; it may be dry, granular and yellow, resembling damp farina of maize; it may be calcified in its outer portion and invested by a firm fibrous envelope. The tubercle may be the seat of general fibroid degeneration, constituting the pearl nodules (perl-knoten) dense as cartilage and either with or without a soft caseated centre; it may show an agglomeration of nodules in all stages from the early congested nodule to advanced caseation or cretefaction, the whole embedded in a solid congested and infiltrated tissue, largely fibroid. There may be extensive abscesses, the seats of complex infections, having thick uneven walls, often showing grape like tuberculous outgrowths, and containing thick, caseopurulent, viscous, granular, yellowish or greenish and comparatively odorless contents; in other cases the abscesses have burst into the bronchia, leaving vomicæ and with the new resultant infections the contents have acquired an offensive putrid odor; finally, there may be extensive inflammatory infiltrations, affecting lobules or lobes, and interspersed with tubercles in the form of the early grayish or transparent nodule, or even more advanced caseous or cretaceous centres. These latter serve to distinguish the condition from broncho-pneumonia, the grayish centres of which might suggest miliary tubercle. The broncho-pneumonia, however, has the whitish centres confined to the bronchioles and their terminal air sacs, and represent their thickened walls and muco-fibrinous contents; they do not show the same tendency to caseation, nor necrosis of the tissue, nor to caseation of the dependent lymph glands, and, above all, they do not contain the bacillus tuberculosis.

433A noticeable feature in the tuberculous lung is the great frequency of tubercles of all different ages from the initial transparent nodule to the caseated or calcified mass side by side. A tuberculous bronchitis is a familiar accompaniment, with lines of miliary tubercles, ulcers and a flocculent (sometimes gritty) muco-purulent discharge, containing elements of the necrotic tissue and bacilli. Emphysema and interlobular œdema are also met with.

The Pleuræ often suffer by continuity of tissue from the diseased lung, but they may be affected primarily through infection of the circulating blood. The earliest pleural lesions may be congestion, exudation and the formation of false membranes in fringes, but soon these become the seats of minute nodules or forming tubercles which steadily encrease to form pale red cauliflower-like growths—which have been spoken of as grapes, from their supposed resemblance to bunches of that fruit. Extensive areas of the mediastinal, costal or pulmonic pleuræ are often completely covered by these productions. Dense, and thick adhesions sometimes form, holding in their substance characteristic tubercles.

The bronchial and mediastinal lymph glands receiving as they do the afferent trunks from the lungs and the great lymph sac of the pleura, offer in their sluggish currents the most favorable culture vessels, and almost always become affected in consequence. Not unfrequently they are found to be tuberculous when the tissues which they drain appear to be sound, and we must therefore, conclude that the primary slight lesions in the latter have recovered, or that the bacilli have passed through the tissues and lymph channels without establishing any centre of disease. The glandular lesions are primarily congestion and redness, with more or less infiltration and swelling, followed by a nodular induration, with enlargement or exceptionally shrinking. When bisected they may show all stages of the tubercle from the miliary granule to the caseous, dry, yellow, granular or cretaceous necrosis. By aggregation these often grow to a large size, a long diameter of 6 to 12 inches being not uncommon.

Pericardial and Cardiac Lesions. The pericardium may be implicated from the pleuræ or independently, and though tuberculosis of the heart is rare, it may be the seat of primary tuberculosis 434or of extension from the pericardium or endocardium. In the N. Y. State Veterinary College Museum is a cow’s heart, greatly enlarged, and completely invested and invaded by tubercle several inches thick.

Tuberculosis of the Mouth and Throat. Tubercles sometimes form in the tongue causing nodular swelling, with a caseated centre. Much more frequently they attack the pharynx or larynx with the formation of nodular necrotic swellings, followed by ulcers and the implication of the adjacent lymph glands. The glands are liable to be invaded through the tonsillar and other follicles of the faucial and pharyngeal regions, which like the solitary and agminated glands of the intestines form excellent culture vessels. The glands most frequently attacked are the retro-pharyngeal, but the lateral pharyngeal, the intra-parotidean and submaxillary lymph glands occasionally suffer. They often become indurated, yet the formation of abscess-like sacs is not uncommon especially in the retro-pharyngeal.

Gastro-Intestinal, Peritoneal and Mesenteric Tubercles. Tubercles of the interior of the stomachs are rare, though they are frequent on the peritoneal surface of the first three stomachs, as rounded, subserous nodules varying in size from a pea upward. The mucosa of the small and large intestines may suffer, by preference in the seats of the solitary or agminated glands, and the resulting ulcers may extend in the lines of the lymph vessels from the convex to the attached border of the gut. The small greenish caseated and calcified nodules on the intestines, which are so often mistaken for tubercles, are the degenerated cysts of the œsophagastoma. Tuberculosis of the mesenteric lymph glands is much more common, the successive stages being essentially like that seen in the bronchial glands. Beside these the surface of the mesentery, omentum and abdominal parietes often becomes the seat of congestion, exudation and cauliflower-like neoplasms or grapes, as already stated of the pleuræ. In a certain number caseation or cretefaction may be detected.

Liver Tuberculosis. The liver is greatly exposed to tuberculosis as the single destination of all the blood from the gastro-intestinal tract. Tubercles also form on its surface by direct infection from the peritoneum. The hepatic tubercles are often very large and numerous, adding greatly to the bulk and weight 435of the viscus. There is usually coincident tuberculosis of the lymph glands of the porta.

Tubercle of the Spleen. This is also a favorite seat of the morbid process, exposed as it is to the reflux of infected blood in the portal vein, and to access of the bacillus from the peritoneum and omental lymphatics.

The pancreas is less exposed to the channels of the circulation and is less frequently affected.

Genito-Urinary Tubercles. The kidneys are always liable to suffer in generalized tuberculosis, in accordance with their function of elimination and the great quantity of blood that passes through them. The tubercles may be numerous, encroaching upon and destroying the glandular tissue, and determining congestion, nephritis and hæmorrhage (Schütz). The ovaries, when tuberculous, lead to nymphomania and sterility; they become swollen, with rounded projections, indurated, and on section show all stages of infiltration, caseation and calcification. They may encrease to a great size. Tubercles are found on the Fallopian tubes, the serous and mucous surfaces of the womb, and in the broad ligaments, in all their characteristic forms. The bladder and vagina are less frequently involved. In the male the testicle, epididymus, tunica vaginalis and prostate vesicles are sometimes affected. The swelling and induration of the affected organ, or the existence of hydrocele, may be noted.

Tubercle of the Udder. From the mass of blood passed through the udder it is specially exposed to infection whenever the bacilli enter the circulation. It may also be directly infected by the entrance through the teat, or a trauma, of the bacillus of the stable dust. There may be for a time only a slight general swelling which leads to no suspicion on the part of the milker, and as the secretion is not arrested, a dangerous product may be distributed. At this stage the lobules on section appear swollen, gray, with paler or yellowish points and minute hæmorrhages. The milk ducts contain coagula and bacilli (Bang). In other cases, usually more advanced, the gland is hard, nodular, enlarged, and shows a marked thickening of the walls of the smaller milk ducts and secreting follicles, with yellowish and even caseous and calcified centres. The gland is often greatly enlarged, the milk suppressed or completely altered, and tubercular neoplasms or ulcers exist in the larger ducts.

436Tuberculosis of the Brain and Spinal Cord. As noted in Volume III. this occurs in young cattle especially in the form of tubercles of all ages attached to the pia or arachnoid, on the brain, or cerebellum, or in the ventricles, also in the cerebral matter, in or on the lumbar enlargement of the cord or on its pia. Several cases have come under my notice in the mature cow.

Tuberculosis of the Eye. This has been seen mainly as a result of experimental inoculation, yet casual cases also occur in the cornea, sclerotic, iris or choroid, the product undergoing early necrosis and softening into a yellow mass filling the different chambers.

Tuberculosis of the Bones. Though less frequent than that of internal organs this is not rare. It usually attacks the spongy tissue, near the articular extremities, or the vascular line between epiphysis and diaphysis, giving rise to considerable exudate, thickening of the bone and arthritis. The vertebræ, ribs, sternum, petrous temporal, frontal and occipital also suffer. Sections of the bone show dilatations of the cancelli, filled with the characteristic nonvascular groups of giant, epithelioid and lymphoid cells with, at times, softened and caseated centres. The adjacent bone is congested and softened, so that the detachment of epiphysis and apophyses is not uncommon. In case of invasion of the joints the cartilages and ligaments are the seat of tubercular deposits, softening, fibroid change and caseation, and there is general synovitis. The cartilages of the ear (concha) and nose (septum) may also be invaded.

Tubercles of the Skin. These are not very uncommon in cattle being the counterpart of the tuberculous warts and ulcers of the hands of butchers, tanners and others that handle the products of diseased animals. They may show as little pea-like nodules in the substance of the skin, or immediately beneath, very commonly on the side of the abdomen, where their presence in life furnishes a useful suggestion, as enlarged masses forming raw, warty projections with centres of caseation, or as clusters of warty-like growths of this kind (grapes).

Tuberculosis of the Muscles. This is comparatively rare in cattle, though by no means unknown, appearing as tubercles of the size of a pea and upward, in or between the muscular masses, often showing a caseated centre.

437Tubercle of Lymph Glands. No organs in the body suffer more than the lymph glands as they receive through their afferent trunks and develop the bacilli coming from any adjacent tissue to which they are subsidiary. There is also evidence to show that bacilli entering from the lungs or bowels may pass through these without apparent effect to develop in the connected lymph glands. The frequent infection of the pharyngeal, bronchial, mediastinal and mesenteric lymph glands has been already sufficiently noticed, and if the other groups suffer less it is mainly because the tissues from which they derive their lymph are less frequently infected. An intimate knowledge of the different groups of lymph glands is a most essential prerequisite to the diagnosis of tuberculosis in life, and no less to a satisfactory post mortem examination. The order of relative susceptibility and importance is somewhat as follows: Bronchial, mediastinal, mesenteric, hepatic, sublumbar, mammary inguinal, subdorsal, phrenic, intercostal (especially the first and second), pharyngeal, parotid, submaxillary, prescapular, prefemoral (stifle), prepectoral, axillary, cubital and popliteal.

Relative Frequency of Tubercle in Different Parts in Cattle. The following table gives the seat of tubercle as noted by a number of observers. It is open to the objection that it is the result of examination for diagnosis, and therefore gives the most obvious rather than the complete list of lesions. Examination of the brain, bones, deep muscles and intermuscular glands, etc., was usually omitted. Again, as the animals were often steers, the indications as regards the generative organs are unreliable. The œsophagostoma nodules on the bowels have been so often mistaken for tubercles that I have omitted all reference to intestinal tubercle.

438

DISTRIBUTION OF TUBERCLES IN DIFFERENT ORGANS OF CATTLE: PER CENT OF AFFECTED CATTLE.

% Right Lung. % Left Lung. % Mediastinal Glands. % Bronchial Glands. % Costal Pleura. % Visceral Pleura. % Mesenteric Glands. % Liver. % Spleen. % Uterus. % Lumbar Glands. % Liver Lymph Glands. % Peritoneum. % Pharyngeal Glands. % Diaphragm. % Stomach. % Udder. % Iliac and Inguinal Glands. % Lymph Glands of Udder. % Lymph Glands of Flank. % Lymph Glands of Shoulder. % Pericardium. % Heart. % Kidneys. % Bones. % Muscles. % Larynx.

German Abattoirs, 75 29 47–55 28 19 10 5 1 4 0.2 0.16 1 0.06 0.9 0.7 0.1 0.13

Pearson, (Penna), 63–57 60.7–33.8 22 23.25 20.7 5.7 5.5 10.3 14 15.15 11.4 7.2 8.75 13.5 9 7.75 8.2 2.1 0.4

Bryce (Canada), 77.27 56.8 11.36 11.36 40.9 45 2.27

Reynolds (Minn. Agr. Ex. Station), 89.4 33.3–64.9 79 12.5 35.4 27 8.3 18.7 16.6 2

Law (N.Y. Grade Herds), 34.8 64 6.4 9.6 1.6 17.7 6.4 6.4

Nelson (N. J. Exp. Station Cows), 33.9 28

Russell (Wis. Exp. Station), 55 72.4 24 10 31 6.9

Stalker & Niles (Ia. Exp. Sta.), 36 61 8.3 5

Reick (Leipsic), 100 ^[2]57 83 18 ^[2]57 17 52 9 49

439Swine. The lesions in swine, though essentially like those in cattle, differ in some particulars. The primary tubercles are more commonly pharyngeal or intestinal and mesenteric, in keeping with infection by ingestion; caseation will often proceed to liquefaction, so that the tubercles appear like grumous abscesses with irregular outlines and vascular growths on their walls; there is less tendency to cretefaction than in cattle; the muscular and intermuscular tissues and the lymph glands are far more frequently affected; ulceration of the pharyngeal and intestinal mucosæ is more common. The lungs, liver, spleen and visceral lymph glands are very subject to tubercle, the kidneys, uterus and testicles somewhat less so, and the nerve centres least of all. The serosæ are often involved and the seat of clusters of vascular or caseated neoplasms (grapes). The bones and joints also suffer, particularly in young growing animals.

Horse. The horse suffers much less frequently than cattle or swine, probably largely because of his outdoor life, his better tone as the result of muscular work, and the absence of the excessive milk secretion which is secured from cows and of the dangers from ingestion that attend on swine. Yet, according to Nocard, it is even more susceptible, and the disease once established is liable to advance more rapidly to a diffuse generalization. The lesions in the lungs and abdominal cavity resemble those of cattle, both in nature and abundance; tuberculous polypi and ulcers are more common; the visceral lymph glands (bronchial and mesenteric) are early and severely attacked; the liver and spleen suffer extensively, the serosæ somewhat less so; lesions have been noted in the vertebræ, skin and muscles (Cadiot). In rare instances tubercles have been seen in the heart, and the aorta has been atheromatous (Cadiot). Necrotic degeneration, caseation and cretefaction occur as in cattle.

Sheep and Goat. Tuberculosis is infrequent in the goat and especially so in the sheep, owing perhaps largely to open air life and their predilection for high, airy pastures. When inoculated they show a marked susceptibility, and under favorable conditions they contract the infection casually. The tubercles may be found in all parts of the body,—lungs, thoracic lymph glands, intestines, mesenteric and sublumbar glands liver, spleen, serosæ, lymph glands at large, vertebræ, etc. There is less tendency to calcification 440than in the ox, the older tubercles remaining in the caseated condition or bursting and forming vomicæ. A common seat of casual tubercle in sheep is around the throat or on the sides of the cranium or face.

More frequently than in cattle, verminous affections (œsophagostoma columbiana, and venulosum in the bowels, stongylus filaria and rufescens in the lungs, linguatula denticula in the mesenteric glands) are mistaken for tuberculosis, hence the necessity for a careful investigation into the nature of the neoplasm, the presence of the tubercle bacillus, and the absence of the worms and their eggs. Except in the case of the linguatula the lymph glands are little affected by the worms.