COMPOSITION OF THE BACTEKIAL CELL. 45 



yielding ethereal extract 0.7 per cent., nitrogen 1.7 per cent., and 

 ash 2.0 per cent. Calculated on the dry substance, the follow- 

 ing percentage composition was arrived at for the microbe in 

 question : 



Ethereal extract (fat, &c.) 

 Albumin (N x 6.25) 



Ash 



Undetermined substances 



Per Cent. 



4.8 

 71.2 



13-5 



10.5 



An examination made by NISHIMURA (I.) of a pure culture of 

 a water bacillus gave the following as the constitution of the dry 

 matter in this microbe : 



Per Cent. 



Albumin . 63.5 



Carbohydrates 12.2 



Alcoholic extract 3.2 



Ethereal extract 

 Ash 



Lecithin . 

 Xanthin . 



Guanin 

 Adenin 



II. 2 



0.68 

 0.17 

 0.14 

 0.08 



The most noticeable figures here are those relating to the content 

 of nitrogen, which show that, in this respect, the bacteria are 

 excelled by but few organisms, while they have no compeers in 

 the vegetable kingdom. To demonstrate this fact more clearly 

 the subjoined figures have been selected, showing the mean nitrogen 

 content in the dry substance of : 



Lean 

 beef. 



Cow's 

 milk. 



Nitrogen per cent. 14.3 4.4 



Soja 

 beans. 



6.0 



Russian 

 wheat. 



3-5 



Truffles. 



Micrococcus 

 prodigiosus. 



5-6 11.4 



The earliest researches on the nitrogenous constituents present 

 in bacteria were carried out by NENCKI and SCHAFFER (I.), both 

 of whom isolated from putrefactive bacteria a nitrogenous sub- 

 stance to which they gave the name of mycoprotein. The highly 

 concordant results of a series of ultimate analyses of this substance 

 gave the following mean values : 



C : 52.32 H : 7.55 N : 14.75 O + S : 25.38 



The percentage ( 1 4. 7 5 per cent. ) of nitrogen found is remarkable, 

 and shows that mycoprotein must have a very different constitution 

 to that of ordinary albumin or protein, which, as is well known, 

 contains about 16 per cent, of nitrogen. The amount of this 

 compound in the dry substance of bacteria is at least 40, and 

 sometimes as much as 50 per cent. Differences are also apparent 

 as regards their behaviour towards reagents, nitric acid, for example, 

 converting albumin into a bright yellow compound, named, on the 

 proposition of MULDER (I.), xanthoproteic acid, whereas mycoprotein 

 does not give this reaction. 



