CHEMICAL COMPOSITION OF BACTERIA. 51 



CHEMICAL COMPOSITION OF BACTERIA. The bodies 

 of bacteria consist of water, salts, and albuminous sub- 

 stances, with smaller proportions of various extractive 

 substances soluble in alcohol or ether, such as triolein, 

 tripalmitin, tristearin, lecithin, and cholesterin. In 

 many varieties substances giving the reaction of starch 

 have been found, while others give the true reactions 

 of cellulose (jB. subtilis). Nuclein has not been found 

 in any of the bacteria, though the nuclein bases, xan- 

 thin, guanin, adenin, have been found. 



The relative amounts of water in bacteria are influ- 

 enced to a large extent by the nature of the medium on 



FIG. 1. 



Zoogloea of bacilli. 



which they have been grown. In like manner the con- 

 tent in albumin, extractive substances, and salts varies 

 with the conditions under which the bacteria have been 

 cultivated. E. Cramer 1 has studied the chemical com- 

 position of bacteria in great detail. As the result of 

 his studies of microspira comma, he found its composi- 

 tion to be as follows : water 88.3 per cent., albumin 7.6 

 per cent., ash 3.6 per cent. The dry substance of the 

 bacteria contains the following : albumin 65 per cent,, 

 ash 31 per cent. From 76 to 80 per cent, of the ash 

 consists of sodium chloride and phosphate. 



In size the bacteria are certainly the smallest living 



1 E. Cramer: Avchiv fur Hygiene, Bd. xiii., xvi., xxii., and xxviii. 



