60 



THE CHEMISTRY OF BACTERIA 



the composition of bacteria markedly. Cramer 1 has found that the 

 percentage composition of the ash of the cholera vibrio varies within 

 very considerable limits as the organism is grown under different 

 conditions. The following table indicates in a general way the influ- 

 ence of these factors: 



IS 



=4 

 II- 



Ash content of bacteria in dry substance 

 Ash content of moist mass .... 

 Ash content of medium in moist mass 

 Phosphoric acid in bacterial ash . 

 Phosphoric acid in media ash 

 Chlorine in bacterial ash .... 

 Chlorine in media ash 



The phosphorus content of the medium in these experiments, as 

 shown in the above table, was varied almost twenty times, but in the 

 bacterial organisms it varied scarcely three times. The variation in 

 chlorine content was somewhat greater. 



Even as important an element as nitrogen is subject to rather wide 

 variations in bacteria, as Cramer 2 and Lyons 3 have shown. The fol- 

 lowing tables summarize Cramer's and Lyons's results. They were 

 obtained by growing certain bacteria mentioned specifically below on 

 a medium consisting fundamentally of 1.5 per cent, agar, to which were 

 added various substances, as indicated in the tables, respectively 

 Media A, B, and C. The general procedure was to grow the bacteria 

 at 37 C. for several days, to wash them off with salt solution, to free 

 them from adherent media by centrifugalization and washing, to dry 

 the washed organisms in vacua to constant weight, and to analyze 

 the dry residue for extractives and ash. 



CRAMER. 



1 Quoted by Kruse, Allgemeine Mikrobiologie, p. 88. 



2 Arch. f. Hyg., 1893, 151. 3 Ibid., 1897, xxiii, 30. 



4 From water. 



