90 JOHNE^S DISEASE 



the bacillus of Johne's disease can be cultivated, 

 either as primary or as subcultures, on media to 

 which bovine tubercle bacilli or extracts prepared 

 from them have been added, and our results would 

 not justify us in stating that in this respect the 

 bovine type is inferior to the human type or to the 

 bacillus phlei. And it ought to be stated particu- 

 larly that our successes have been obtained with 

 quite typical bovine baciUi, isolated directly from 

 bovine lesions by ourselves, markedly dysgonic, 

 and proved by experiment to be virulent for bovine 

 animals and rabbits." 



The results obtained with the bovine type by these 

 authors are certainly different from those obtained by 

 ourselves, and given in our paper in the Proceedings 

 of the Royal Society and later in the Centralhlatt fur 

 Bakteriologie. The different results are probably 

 accounted for in part, at least, by the difference in 

 the media on which the bovine tubercle bacilli were 

 grown. Experiments bearing on this point are described 

 later in this chapter. 



The authors (M'Fadyean, Sheather, and Edwards), 

 however, appear to have misunderstood our remarks 

 on the relationship of the human and bovine types of 

 tubercle bacilli. We made an observation incidentally 

 on this point, and suggested that the differences we 

 had found were worthy of further investigation. At 

 the same time we pointed out that we did not consider 

 that the different results we had obtained with the two 

 types represented an important biological difference, but 

 that the difference in the bacilli was probably physio- 

 logical in nature. Our remarks were : 



** Whatever this difference between the two 

 types of bacilli may be due to, it does not in our 



