the nose. This was removed; the wound quickly healed. Eight or nine months later the child suffered from caries of the tarsi. In the second case a nodule appeared on a boy's chin, and a few weeks later a tuberculous caries of one of the vertebræ followed. In cases of skin inoculation there is as a rule strong hereditary predisposition—that is, great susceptibility to take the infection. Von Wehde1 tested the infectious character of the air of rooms inhabited by the phthisical, by exposing plates wetted with glycerin, and then inoculating guinea-pigs with the dust obtained; but the latter remained free from tuberculosis, hence he concluded, the expelled air of the tubercular could not infect, and that also tuberculous sputum so long as it was moist released no spores. Celli and Guarnieri,2 Sirena and Pernice, and Nicolas, obtained similar results. On the other hand, Theodore Williams,5 by placing a glass smeared with glycerin for five days in a ventilating-shaft, at Brompton Hospital, was able to recognise the tubercle bacillus. Sirena and Pernice placed guinea-pigs in a flask in which powdered sputum was shaken up frequently, but neither by inhalation nor by injection into the trachea could they ever excite tubercle; inoculation alone was active. Celli and Guarnieri could but exceptionally excite tubercle by inhalation experiments, only when the mucous membranes were previously irritated by breathing irritating gases. 8 The researches of Muller, Truomi, are also to be mentioned; both succeeded through the injection of tuberculous pus in the arteria nutritia tibiæ of goats, or by the introduction of tuberculous matter into the joints of rabbits, in causing typical tuberculosis of the bones and articulations. There are also to be remembered the researches of Spillmann and Haushalter,10 and E. Hoffmann,11 who succeeded in proving that the abdomen and the excrements of flies which suck the sputum of the phthisical, contain the tubercle bacilli, so that, therefore, flies may be the medium of tuberculous infection. 1 Bollinger, zur Aetiologie der Tuberculose. München, 1883. 2 Gazzette d. ospit. 1883. 3 Arch. f. Scienz. Med. Bd. IX.; Union Med. 1886, No. 80. 6 Ibid. 8 Zeit. f. Chirurgie. Bd. XIV. 10 Compt. Rend. T. CV. Gazz. d. ospit. 1885. 5 The Lancet. 1882. 7 Estr. d. Atti. Acad. Med. di Roma. 1886, 1886. 9 Giorn. internation. d. Scienz. Med. 11 Public Health, vol. i. 220. E. Hoffman artificially fed flies with phthisical sputum with a positive result; they became feeble, with increase of the excreta, and soon died. The intestinal contents of infected flies inoculated into the anterior chamber of the eyes of nine guinea-pigs gave positive results in five cases. (349) The Production of Tubercles in Animals by Feeding them with Tuberculous Products. Wesener1 made a number of researches on the production of tubercle in rabbits from food; for this purpose he used sputum fresh or putrid, or after treatment with various digestive fluids. The feeding was exclusively milk with the addition of alkali. The result was always positive with simple feeding by fresh tuberculous sputum, so also with dry and putrid sputum, tuberculosis of the mesenteric glands being first produced, and next that of the intestine liver and spleen. Direct injection into the intestine. much accentuated the process. Treatment of the sputum with different digestive fluids, drying, and putrefaction, did not destroy the infectious matter. Wesener thought that the spores preserved their characters when the bacilli were destroyed in the stomach. If the number of spores is so small that the lymph apparatus can get rid of them before they multiply, no infection occurs; if a larger number remain in the mesenteric glands, an inflammatory centre at first forms without bacilli, later these farther develop, but if the bacillary material is injected direct into the intestine, very soon tuberculosis of the intestine is produced. Tuberculosis of the mesenteric glands he refers also to the ingestion of milk with few spores. 3 Fischer 2 and Baumgarten partly arrived at other results than Wesener, they could by once feeding with milk to which had been added tuberculous juice, excite tuberculosis of the intestine, the mesenteric glands and liver of rabbits. They farther assert that the tubercle bacilli when spore free withstands the action of the digestive juices. In opposition to Wesener's results they found 1 Kritische u. exper. Beiträge zur Lehre v. d. Fütterungs-Tuberculose. Freiburg, 1885. 2 Archiv. f. exper. Pathol. Bd. XX. 3 Centralbl. f. klin. Med. 1884, No. 2. that the intestine was first affected with tuberculosis, and subsequently the mesenteric glands. The unwounded mucous membrane of the mouth and throat could absorb tubercle bacilli in the food by means of the lymphatic apparatus. Professor Straus placed, during from one hour to forty-eight hours, spore cultures of the bacillus of Koch in contact with the pure gastric juice of a dog. After six hours the bacilli had lost none of their virulent action. After twenty-four hours this action was destroyed. It may thence be seen that the tubercle bacilli are not rendered inoffensive by their sojourn in the stomach. Nevertheless, the gallinaceæ appear to be rarely infected with tuberculosis through the intestinal canal. M. Straus had given daily to fowls during several months, enormous quantities of the sputa of phthisical subjects. In none of the fowls was there any trace of tuberculosis, not even in those which in one year had swallowed as much as fifty kilogrammes of tuberculous sputa. Bollinger1 observed tuberculosis of the intestine, liver and spleen in three fowls which had fed on tuberculous sputa in the court of an hospital. (350) Unequal Susceptibility of Different Animals to the Tubercular Infection. In the numerous experiments on animals which have been made it has been found, as might be expected, that some are more predisposed to the infection than others, for instance Daremberg 2 draws from his researches the conclusion that in animals the tuberculosis produced by inoculation depends as to its character on the kind and age of the animal, as well as on the activity and quantity of the tubercle bacillus. If the tubercle bacilli are cultivated at 38° C., and introduced by trepannation into rabbits and guinea-pigs, the animals are killed in from twenty to thirty days by miliary tuberculosis; but in a cock and a dove treated in the same way, the first died in six or seven months. A culture at 50° excited in a rabbit only an indolent abscess, the pus of which killed young rabbits in several weeks, whilst old rabbits after some months showed no change. 1 Bayrisches ärtzl. Intelligenzblatt. 1883, No. 16. It has yet to be proved that any warm-blooded animal is exempt from tuberculosis; some, like the horse, rarely suffer from this malady, but even in the horse spontaneous tuberculosis is not extremely rare, and cases have been described by Johne, Coker, Nocard, M'Fadyean, Campbell, and Freer. (351) Giant Cells. Koch was of opinion that the beginning of tubercle was the entry of a bacillus into an epithelial cell, which cell may wander from its original seat. The pathogenetic action of the bacillus causes changes in the surrounding cells. The epithelial cell itself is converted into a "giant cell." This account of the origin of giant cells is much disputed, some see in the giant cell a lymph space with proliferating endothelial cells. In some cases Weigert has proved that the giant cell is a collection of cells in which bacilli are causing proliferation at the margin and fusion and degeneration in the centre, the end result being a mass of caseous material in the centre and at the margin proliferating cells with bacilli between them. Klein has scen giant cells produced by the fusion of the epithelial cells of the air vesicles. Small blood vessels, the seminiferous and the lacteal tubules have all been described as developing into giant cells. developing into giant cells. "The presence of these giant cells affords evidence that the cells are making a determined resistance against the advances of the bacilli, are giving way slowly, and so limiting the area of caseation. In many cases where the giant cells with their rings of nuclei are best marked, very few bacilli are to be found, as they have been destroyed by the phagocytes at the margin-i.c., the active cells with deeply stained nuclei. In other cases, however, the bacilli have taken the place of the nuclei at the margin of the giant cell, the boundary line in such cases being determined for a time by the basement membrane of the tube in which the mass is formed." Once the tubercle bacillus gains access to the deeper tissues, it depends on two things whether the bacilli will infect or no, viz. (1) on the numbers of the bacilli themselves, and (2) on the tissue resistance. Should they arrive in large numbers, few tissues will resist the invasion; should they arrive in moderate numbers, the |