EXPERIMENTS WITH PURE CULTURES 153 



were found. The mesenteric glands were consider- 

 ably enlarged, but in these we were unable to demon- 

 strate the presence of Johne's bacillus. 



Sheep No. 5 showed no definite thickening of the 

 intestine, but several acid-fast bacilli were found in 

 the walls of the ileo-caecal valve. The mesenteric 

 glands were much enlarged and presented the typical 

 appearance of Johne's disease, although only a few 

 bacilli were present. 



These experiments are interesting, since they prove 

 that Johne's bacillus, isolated from a naturally infected 

 bovine, is pathogenic for sheep, and is capable of 

 producing a condition in these animals which is 

 identical with that found in cattle, and we feel justified 

 in assuming that the disease in naturally infected cattle 

 and sheep is caused by one and the same micro- 

 organism. 



The Pathog-enicity of the Bacillus for Small Animals. 



— Numerous attempts have been made to infect the 

 smaller laborator}^ animals, such as rabbits, guinea- 

 pigs, etc. As we have already mentioned, the earlier 

 investigators, Johne and Frothingham, B. Bang, etc., 

 used portions of the diseased bowel obtained from 

 cattle suffering from this condition. The results, 

 except when the inoculated material also contained 

 tubercle bacilli, appear to have been entirely negative, 

 indicating that these animals are endowed with a 

 natural immunity against the disease in the same way 

 as they are immune to the human lepra bacillus. 



At the Brown Institution, working with pure cultures, 

 the authors have inoculated pigeons, hens, rabbits, 

 guinea-pigs, mice, and rats, subcutaneously and intra- 

 peritoneally, while several pigeons, hens, and rabbits 

 were inoculated intravenously. These animals, to- 

 gether with some mice, rats, and rabbits, which were 



