456 Veterinary Medicine. 



placed 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 suit- 

 able 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 be- 

 lieve that the microbe has lived, an*d finder 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 inocula- 

 tion, 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 patho- 

 genesis 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 



