CULTIVATION OF THE BACILLUS 69 



and other substances. The cultures were placed in 

 an incubator at 39** to 40° C. On none of these media 

 could any definite growth of the bacillus be detected. 



With the object of testing for the possible presence 

 of an ultramicroscopic virus working in symbiosis 

 with Johne's bacillus, we prepared an extract of the 

 infected intestine of a cow suflfering from Johne's 

 disease and passed it through a Doulton white filter. 

 The sterile filtrate so obtained was added to various 

 media, and the whole series inoculated with small 

 portions of intestine affected with Johne's disease. 

 These media all gave negative results. 



From the experiments conducted on this case we 

 came to the conclusion arrived at by most other 

 workers, namely, that the specific bacillus would not 

 grow on any artificial medium known to bacteriologists, 

 and that if successful cultivation were to be achieved, 

 some new medium would have to be prepared. We 

 considered also that the failure of growth of the specific 

 bacillus must be due, either to the poisonous action of 

 some substance in the medium, or to the absence of 

 some foodstuff or stimulant necessary for its vitality 

 and growth. 



At the same time we were struck by the apparent 

 close relationship existing between this micro-organism 

 and the tubercle bacillus ; and as the bacillus of pseudo- 

 tuberculous enteritis and the tubercle bacillus both 

 grow in the same species of animal, we thought it 

 highly improbable that there could be any substance 

 in the ordinary laboratory media which would act as a 

 poison to the one bacillus and not to the other. This 

 possibility was accordingly excluded, and we were 

 forced to conclude that the failure to grow the bacillus 

 must be due to the absence of some necessar}'- food- 

 stuff. 



