94 JOHNE^S DISEASE 



even in this case, was not so good as the human 

 type. We also obtained some positive results with a 

 bovine strain grown on glycerine-beef broth, but here 

 again the results were not nearly so good as with 

 B. phlei. 



A similar experiment was carried out with a freshly 

 isolated strain of Johne's bacillus grown on the 

 timothy-grass bacillus-egg medium, and with a strain 

 of Johne's bacillus acclimatized to grow without the 

 essential substance and grown on ordinary glycerine- 

 peptone-beef broth. In this experiment a freshly 

 isolated strain of Johne's bacillus grew on an ^gg 

 medium in which was incorporated i per cent, of the 

 dead acclimatized Johne bacilli which had been grown 

 on the glycerine-beef broth ; but, on the other hand, 

 it failed to grow on an Qgg medium in which were 

 incorporated the dead bodies of a freshly isolated 

 Johne bacillus which had been grown on an Qgg 

 medium containing i per cent, of dead B. phlei. Thus 

 we obtained the same result with Johne's bacillus 

 as with the bovine tubercle bacillus. This experiment 

 shows also that Johne's bacillus has not become 

 acclimatized to grow without the essential substance, 

 but that it has acquired the power of forming it from 

 the medium ; and it is interesting to note that the 

 strain of Johne's bacillus that has become acclimatized 

 to grow on glycerine-beef broth still gives no growth 

 on ordinary Dorset's egg medium. So presumably it 

 cannot form the essential substance from that medium, 

 although, of course, like an unacclimatized strain of 

 Johne's bacillus, it will grow well on the tgg medium 

 if it contains some essential substance obtained from 

 some other acid-fast bacillus, including the same 

 acclimatized strain of Johne's bacillus grown on 

 ordinar}^ glycerine-beef broth. 



