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 recently 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 by 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 were 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.

Feeding 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, or 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 lymphoid 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 lungs, 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 seats 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.

A 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 or 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 of 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.

Tuberculosis 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.

Tubercle 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.

Swine. 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 than 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.

Dog and Cat. The lesions are often concentrated on the respiratory or alimentary tract, but they have been noted also in the pharyngeal glands, tonsils, posterior nares, serosæ, liver, pancreas, spleen, nerve centres, ovary, uterus, testicle, epididymus, tunica vaginalis, prostate, heart, aorta, bones and joints. They follow the regular development of bovine tubercle, and caseation and cretefaction are prominent features. These animals are especially liable to infection by eating the left victuals from the plate of a consumptive owner, as well as by devouring consumptive prey, and the primary lesions are to be looked for along the line of the throat, bowels, liver and lungs. For the dog Cadiot records caseating polypi and ulcers on the mucosa of the larynx, trachea and bronchia, and Müller and Cadiot several cases of pharyngeal caseating adenitis in the dog bursting externally and developing intractable fistulæ, having abundance of bacilli in the discharge. These he attributes to expectorated virus from old standing tubercles in the chest infecting the pharyngeal mucosa and indirectly the lymph glands. The infection entering with the food and lodging in the follicles of the tonsils would act in the same way, and infected wounds received in fighting must also be quoted. Cats suffer from similar intractable sores, some of which may be traced to a tuberculous origin. The lungs are often extensively hepatized and of a general pale grayish color, but the early miliary lesions, the caseating and cutaneous centres, the vomicæ often intercommunicating, the tuberculous bronchial and mediastinal glands and the bacilli show the true nature. Intestinal ulcers are common, especially on the agminated glands, and small tubercles, in all stages of degeneration are met with in the enlarged liver, the spleen, pancreas, kidney, etc.

Apes and Menagerie Animals. In these tuberculosis is common alike in the thoracic and abdominal forms, and the lesions in the main are those of domestic cattle.

Chickens. The lesions are common in the abdominal cavity, the intestines, liver and spleen being the most frequently attacked, while the subcutaneous connective tissue, bones and joints also suffer. The lungs and kidneys usually escape. The intestinal mucosa shows small nodules, often caseated, or ulcers; the enlarged and friable liver is studded with tubercles from the size of a hemp seed upward, gray or translucid, homogeneous or with central necrosis, simply or in conglomerate masses, with congested or hæmorrhagic periphery; the spleen is swollen and permeated by similar deposits; fibrinous ascitis is not uncommon; the abdominal lymph glands are enlarged and congested.

The early tubercle shows a central, necrotic, hyaline area, consisting of the debris of disintegrated cells, which is colored brown by picro carmine, unlike the nucleus of the pheasant tubercle (Cadiot). Around the hyaline centre is a zone of large epithelioid cells, the nuclei of which stain strongly in carmine. Outside this is the usual zone of small, round, lymphoid cells. In the whole the tubercle bacilli can be made manifest by the carbol-fuchsin (Ziehl-Neelsen) stain. In the older and larger tubercles the central necrotic mass has encroached in part or in whole on the epithelio-lymphoid zone.

Pheasant. The lesions have the same seats and naked-eye aspect as the chicken tubercle, but under the microscope the smallest and most recent tubercles show epithelioid cells to the centre, or later, the central zone presents a dense fibrous network enclosing open spaces and giving a mahogany stain with Lugol’s solution (iodine and potassium iodide). (Cadiot). There has been an organisation of connective tissue which has submitted to amyloid degeneration, making a clear distinction from the tubercle of chicken.

Parrot. The lesions were thus located by Eberlein and Cadiot:

The skin lesions are vascular neoplasms containing bacilli and usually invested with a covering of horn, but sometimes, on the legs and feet raw. The morbid growth may be rounded or conical, narrowing to a point. The lesions of the buccal mucosa begin as small, grayish swellings on the angle of the mouth, palate, tongue or larynx which grow out into more or less rounded vegetations. The lesions of the liver and lungs are mostly miliary with the usual tubercular features, but they may grow to larger size, as a pea or bean. In the cancelli of bones and on their surface, the lesions resemble those of the mammal.

The cutaneous form has been held to be the counterpart of warty lupus of man, the more plausibly that the disease is developed by inoculation from tuberculous men. The arthritic type represents what is described as gout in parrots.

In any case the recent miliary lesion presents the true tubercular type of a central giant cell or cells with bacilli, surrounded by epithelioid cells, and they in turn by small, rounded lymphoid globules.

PRIMARY AND SECONDARY INFECTION.

The estimate of the relative, early or late infection of two organs or tissues may often be made with reasonable accuracy from the fact that the lesions in one organ are old, caseated, calcified or sclerosed, while those in the other organ are all recent, with vascular environment and almost devoid of caseation or other degenerative process. We cannot safely predicate our decision on the greater number of old lesions in one organ rather than another, as the disease may have advanced much more rapidly in the one tissue. Still less can we state with certainty that the disease has not entered by a given channel because no lesions are left to show the transit of the bacillus along its supposed course. We frequently find tuberculosis of the bronchial or mesenteric glands, when we can detect no lesion in the lung, nor intestine. The bacillus has been passed on without establishing any lasting lesion in transit.

It is often too confidently asserted that the infected dust inhaled, falls directly on the air cells and determines the extensive pulmonary tuberculosis that ensues. So, on the other hand, it is often too arrogantly assumed that tubercle bacilli ingested with food, must necessarily show their results mainly in the intestines, mesenteric glands and liver. That solid particles can find their way directly into the lungs, has long been demonstrated by the pulmonary anthracosis of the miner, and the deadly phthisis of the stone hewer and cutler. The experiments of Cornet, Tappeiner and others in producing pulmonary tuberculosis, by compelling the inhalation of infected spray, corroborate this experience very satisfactorily. Yet it does not follow that all of the offensive matter penetrated the air cells at once on the air inhaled. The heavy particles of steel, quartz and even of coal dust must be mainly arrested on the surface of the moist air passages, yet, under the irritation caused by their presence and the consequent arrest of the ciliary motion, they would slowly gravitate downward to the pulmonary cells. In the case of the inspired tubercular spray or dust, we must recognize the possibility of the approach of the bacillus to the lungs through the lymph and blood channels as well. The bacilli lodged in the pharynx, and, above all, in the tonsillar follicles, can readily enter the lymph vessels, and are finally poured into the lower end of the jugular vein, but a few inches from the right heart, by which they are instantly propelled into the lungs. If then the lung is the most receptive and least resistant organ, it may easily be that this is the first point where the bacillus can establish a strong and effective colony. Apart from this the colonization of the tonsillar follicles may determine a constant supply of fresh bacilli, which may gravitate down with the abundant mucus toward the lungs.

This tuberculous colonization of the tonsillar follicles is doubtless the main source of the infection of the pharyngeal lymph glands, which is so common in ox, pig and dog. It tends further to intestinal tuberculosis through the frequent swallowing of the products of the infected follicles. Then the infection of the pharynx and tonsils, whether established by inhalation or deglutition, may be the first step toward a secondary infection of the intestines.

Again the bowels can be infected by the frequent swallowing of the expectorations brought up from the diseased lungs or bronchia.

Conversely the lungs may be easily infected secondarily from preëxisting disease of the abdominal organs, and again primarily through the lymph channels. With tuberculosis of the cardia or liver the bacilli can follow the lymph vessels of the œsophagus or vena cava so as to reach the mediastinal glands, and from these glands in a state of disease they can easily pass into the adjacent pleural cavity and reach the lung. Or by following the mesenteric lymphatics they reach the thoracic duct and enjoy what is virtually for them a culture fluid, until discharged into the jugular, which, as already stated, is but a few inches from the right heart and lung.

Extension through the general blood stream usually takes place only when tubercles have already become numerous and extensive in a given region of the body, and its occurrence is the signal for a generalized tuberculosis.

The extension from the gastro-intestinal organs, pancreas and spleen may be considered as a partial exception. Here the infecting blood is not the general blood stream, but has to run the gauntlet of the liver capillaries by which the bacilli may be sifted out and delayed. This arrest subjects the liver to secondary tuberculosis in almost all cases of abdominal tuberculosis, and goes far to explain the extraordinary frequency of the disease in this organ. Ingestion tuberculosis almost necessarily leads to hepatic tuberculosis, and this notwithstanding that the primary lesion may have been very circumscribed.

The tuberculization of such a large vascular organ as the liver, however, paves the way for further extension, and if once extensively diseased, the early generalization of the infection is to be dreaded.