166 CONTAGIOUS DISEASES OF DOMESTICATED ANIMALS. 



Bollinger produced tuberculosis iu pigs by prolonged feeding of the 

 milk of tuberculous cows. 



The subcutaneous inoculations of Villemin and his successors were 

 hotly disputed on the ground that they gave rise to Icvsions analogous to 

 those produced by inocculatiou with non-tubercular matter. These were 

 practicully settled by the intraocular injection of white rabbits with 

 tubercular matter by Cohnheim, Salomonsen, Hansell, Deutschmann, 

 and Baumgarten. After an incubation of twenty to thirty days there 

 appeared in the pigmentless eye distinct tubercular nodules, and this was 

 followed by a generalized tuberculosis. Baumgarten develojied tuber- 

 culosis in the eye by injecting the blood of tuberculous animal infected 

 by inoculation. In test experiments with the blood of healthy animals 

 the eyes remained sound; w!ien he used the blood of septica^mic patients 

 intense intiaiiimation of the ey<^ ensued, but never tuberculosis. 



Toussaint found the tubercular lung products of cows constantly in- 

 fecting to rabbits and pigs alter they had been subjected to 55^ to 58° 

 0. in a water bath, and even after they had been roasted like a beef- 

 steak in the gas tlame. He found the nasal discharges, the saliva, and 

 the urine infecting, and as already noticeil the lymph of a vaccine 

 vesicle. Ljdtin concludes : 



Tb.at tuberculosis is contagious, like glanders or lung plague, and that contagiou 

 fills a more important role than heredity in the propagation of the disease. 



As showing the identity of tuberculosis iu man and animals, Koch's 

 demonstration of the bacillus tuberculosis must occup3' a prominent 

 place. The disease had already been proved a hereditary and an infec- 

 tious one, and this organism, found in the growing tubercle of man and 

 animal alike, suggests itself at once as the morbitic germ. It is found 

 alone and unmixed with any micrococcus, in deep seated tubercles, which 

 have had no exposure to the air, while in sputa, vomicje, and other 

 tubercular products exposed to the air a multiplicity of other organisms 

 abound. In all cases f»f rapidly growing tubercles the bacillus is present 

 in great numbers, while in those of slow formation they are scanty. 

 These bacilli have a length of half the diameter of a red blood globule 

 and a breadth of one-fifth of their length ; they are motionless and form 

 spores within the body even during the life of the animal. 



After many attempts Koch succeeded in procuring a pure culture in 

 blood serum of cow or sheep in a preparation of gelatine, on which the 

 bacillus appears as fine scales at the end of two weeks. Thej" grow so 

 slowly that it is only at the end of the third or fourth week that the mass 

 attains the size of a poppy seed. It does not develo]) save at a temper- 

 ature of 3(P to 41° C These peculiarities of culture identify the para- 

 site. 



Tlie bacillus, whether derived from the tubercle of man or that of ani- 

 mals, always shows the same form and the same habits during culture, 

 and on inoculation has produced the same pathological lesions, imply- 

 ing the essential identity of the two. 



I 



