contact with animals already tuberculous, or from tuber- 

 culous materials left in laboratories by previous subjects 

 of the disease. Cohnheim repeated his experiments on 

 rabbits and guinea-pigs, isolated both from other animals 

 and from the stalls in which animals had been previously 

 confined. The subcutaneous or intraperitoneal intro- 

 duction of mechanical and chemical irritants was under 

 these circumstances followed by tuberculosis in not a 

 single instance. Frankel, who had performed with 

 Cohnheim the original successful experiments in the 

 Berlin Pathological Institute, repeated them in his pri- 

 vate dwelling, with absolutely negative results. Cohn- 

 heim, with the moral courage born of true scientific spirit, 

 published this fact, and acknowledged the justice of 

 Klebs' suggestion. 



Chauveau, Aufrecht, Bollinger, and others proved 

 that tuberculosis can be induced in rabbits and other 

 animals by simply mixing with their food tuberculous 

 material, and that this tuberculosis begins not in the 

 lungs, nor in some caseous inflammatory product, but 

 directly in the intestinal wall. Giboux placed healthy 

 rabbits in cages in each of two rooms ; into one room 

 was passed, for several hours a day, the breath expired by 

 phthisical patients ; into the other room the same, after 

 filtering through carbolized tow ; in a few months the 

 rabbits in the first room were dead of tuberculosis ; in 

 the second apartment there was no sign of death nor of 

 tuberculosis. Tappeiner, and after him Bertheau, de- 

 monstrated that the inhalation of sputum from phthisical 

 patients in minute quantity is followed by pulmonary, 

 and then general tuberculosis, not only in rabbits, which 

 are so susceptible to the disease, but even in dogs ; and 

 that the inhalation of other sputum did not produce this 

 effect. On the other hand, Schottelius observed among 

 the inflammatory products following the inhalation of 

 irritant particles, such as malodorous cheese, certain 

 nodules histologically identical with spontaneous tuber- 

 cle ; and that similar nodules sometimes followed the 

 prolonged inhalation of non-phthisical sputum in large 



