CHEMICAL COMPOSITION. 



31 



Yet there is much greater difference in the dry substance 

 of the cholera vibriones, if they are grown at one time 

 upon soda bouillon rich in albumin, and again upon 

 Uschinsky's medium, free of albumin. Cramer here found 

 as follows (the figures are the average from observations 

 upon five cholera cultures): 



Albumin Ash 

 Cholera vibriones on soda-bouillon ... .65;!^ 31% 



Cholera vibriones on Uschinsky's solution . . 45 11 



He found also in the latter case a considerable quantity 

 of non-nitrogenous bodies, a part of which may be thought 

 to be hydrocarbons (or fats). 



For the analysis of the ash of bacteria, consult Cramer 

 (A. H. xxviii) and de Schweinitz and Marion Dorset (C. 

 B. xxiii, 993). The latter found almost only phosphate 

 in the ash of tubercle bacilli. 



Of importance for the classification, even though more in a critic- 

 ally negative sense. Is the fact, discovered by Cramer, that closely re- 

 lated varieties, which, upon many nutrivnt media, present analogous slightly 

 varying composition, suddenly upon a new medium conduct themselves dif- 

 ferently. Most interesting in this respect is the behavior of five cul- 

 tures of cholera, which in soda bouillon furnished vibriones of almost 

 exactly the same composition, but upon Uschinsky's ^ solution pre- 

 sented very variable composition. 



This result shows again how dangerous it is to make a 

 separation of two varieties because of any single chem- 

 ical or biological reaction. In order to understand the 

 astonishing differences, it is only necessary to recognize 

 the ability of one of these varieties to form thick cell- 



' Compare p. 33. 



