THE BACILLUS FOR SMALL ANIMALS 165 



inoculated intravenously, it is highly probable that all 

 the varieties are excreted, to some extent at least, by 

 the kidney. It is easy to understand the negative 

 cultural results obtained v^^ith the fish tubercle bacillus 

 and with Moeller's grass bacillus, both of which are 

 probably rapidly destroyed in the animal body owing 

 to the existing temperature ; it seems, however, rather 

 curious that it is impossible to obtain cultures of 

 Johne's bacillus, since the temperature here does not 

 come into play. It must be remembered that only a 

 limited number of animals have been used in these 

 experiments, so that a certain amount of reserve must 

 be exercised in drawing conclusions from the results. 



The Resisting Pozver of Johne's Bacillus to the De- 

 structive Agents in the Animal Body. — While showing 

 a high degree of resistance to decolorizing reagents, 

 such as mineral acids and alcohol, Johne's bacillus is, 

 at the same time, very difficult to destroy in the animal 

 body. As we have seen, when inoculated into the 

 peritoneal cavity of rabbits, the bacilli are rapidly 

 phagocytosed ; but they may be found a month later 

 within the leucocytes, resisting well, after staining, 

 decolorizing reagents, and being either normal in ap- 

 pearance, or, at the most, somewhat granular. B. phlei 

 and the human tubercle bacillus are also rapidly 

 phagocytosed, but they soon disappear almost entirely 

 from the peritoneal fluid, and the same has been found 

 to occur in the peritoneal cavity of mice. Caseous 

 nodules produced by tubercle bacilli in the peritoneal 

 cavity contain but few bacilli, while those caused by 

 Johne's bacillus may be crowded with bacilli. In 

 rabbits immunized by repeated subcutaneous inocula- 

 tions of dead human tubercle bacilli, and subsequently 

 inoculated into the peritoneal cavity with living bacilli 

 of the same species, or with Johne's bacillus the 



