CHEMICAL COMPOSITION OF BACTERIA. 651 
position of bacteria, quantitatively, by the studies of 
Cramer, though so far only a few species have been 
thoroughly investigated. The percentage of water 
contained in bacteria grown on solid culture media, as 
well as the amount of ash, depend largely on the 
composition of the media. Thus the bacillus prodigio- 
sus when grown on potato contains 21.5 per cent. of 
dry residue and 2.7 per cent. of ash ; when cultivated 
on turnips it contains 12.6 per cent. of dry residue and 
1.3 per cent. of ash. Beside the concentration of the 
culture, its temperature and age also influence the 
amount of residue and ash produced. The residue 
varies, moreover, in its composition in the same species 
under the influence of the culture media employed. 
Thus the Friedlander pneumonia bacillus grown on 
nutrient agar containing peptone yields of residue: 
With 1 percent. With 5 per cent, 
peptone. peptone. 
Nitrogenous matter . 71.7 per ct. 79.8 per ct. 
Extractives . : » 10.3 a 11.3 ee 
Ash. : : . 13.9 Be 10.8 is 
With 1 per ct. peptone 
+ 5 per ct. glucose. 
Nitrogenous matter . ‘ ; . 68.6 per ct. 
Extractives  . : F . 3 . 22.7 = 
Ash ; é = : F : . 7.8 ue 
It would thus appear that an additional quantity of 
peptone in the culture media tends to increase the per- 
centage of nitrogenous matter in the bacillus, while 
the addition of glucose decreases it. 
The cholera spirillum shows still greater variations 
in the residue when grown in soda bouillon containing 
albumin than in Uschinsky’s medium, which is free 
from albumin. Thus Cramer found as an average 
