iv.] ARTIFICIAL COMMA-BACILLI. 63 



latter some liquefy it with a smooth circular outline, others 

 with an irregular serrated line ; in some the liquefied gelatine 

 is clear throughout the circumference and extent of the colony 

 except for a central opaque speck ; in others the liquefied 

 area is uniformly turbid, and so on. By careful examination 

 and re-inoculation of nutritive gelatine or Agar-agar on 

 plates and in tubes the different species characterised by 

 the different appearances just named can be isolated and 

 studied. 



The same can be observed in the case of bacilli and 

 bacteria, i.e. a different mode of growth as regards rapidity 

 of increase or size of the colonies after a certain time, and as 

 regards colour, aspect, outline, and microscopic characters 

 of the organism constituting the colonies. To say, therefore, 

 that such or such an organism in plate-cultivation and in 

 tubes presents such and such peculiar characters, means 

 nothing more than that such and such an organism is of a 

 definite species, and, as we have said, the greater majority 

 of the bacterial species are possessed of such special charac- 

 ters. I never said that the choleraic comma-bacilli cannot in 

 cultivation be distinguished from other bacteria. If any one 

 thinks I did, I can only answer that he has misunderstood 

 my meaning, and at the same time has failed to apprehend 

 the simple fact demonstrated by Koch himself, that almost 

 all the different species of bacteria show under cultivation 

 different cultural characters, by which they are more or less 

 easily distinguishable one from another. I say the possession 

 of cultural characters is not peculiar to comma-bacilli. This 

 is something quite different from saying that the cultural 

 characters of comma-bacilli are the same as those of septic 

 bacteria. 



What are, then, the characters shown by the choleraic 

 comma-bacilli in artificial cultivations ? 



