in CHAUVEAU'S EXPERIMENTS 127 



an instance. Here is that much investigated anthrax 

 bacillus. Many bacteriologists have tried to determine 

 morphological variations of the species through various 

 experimental methods, hoping to see it assume quite 

 different characters : but they have utterly failed. 

 Professor Chauveau studying the same general topic 

 of variability, has investigated it not on the morpho- 

 logical side, but on the physiological one. And he 

 asks very appropriately whether a bacillus which has 

 entirely lost its virulence, while retaining its morpho- 

 logical appearance which is always very simple 

 has not varied more than a bacillus in which form 

 might have varied while the pathogenetic properties 

 had remained unaltered ? The answer seems to me 

 manifest, that variability of virulence is of greater 

 importance than that of form and external appear- 

 ance, especially in the case of such very simple and 

 undifferentiated organisms, since this testifies to 

 deep modifications in the chemistry and vital pror 

 perties of the organism. How much more would 

 this be evident if the new characters acquired by 

 the organism were to remain unaltered from one 

 generation to another, without it being necessary 

 to provide permanently the special conditions or 

 the peculiar environment which initiated the produc- 

 tion of new characters ? And this case is not of 

 hypothetical nature ; it really exists, and I have been 



