COMPOSITION OF THE BACTERIAL CELL 35 



for purposes of future microscopical comparison. The preparation of such is 

 described in all the books just mentioned. 



36. Elementary Composition of the Bacterial Cell. 



Determinations on this point by micro-chemical analysis were first attempted 

 by KAPPES (I), whose attention was principally devoted to Micrococcus prodigiosus, 

 cultures of which were made on solid nutrient media, and then, when they had 

 arrived at sufficient development and had expanded into mass cultures, examined 

 for the amount and composition of the dry matter therein. Cultures of this 

 fission fungus on agar-agar contained on an average : Water 85.5 per cent., and 

 dry matter 14.5 per cent., the latter yielding ethereal extract 0.7 per cent., 

 nitrogen 1.7 per cent., and ash 2.0 per cent. Calculated on the dry substance, 

 the following percentage composition was arrived at for the microbe in question : 



Ethereal extract (fat, &c.) 

 Albumen (N x 6.251 

 Ash .... 

 Undetermined substances 



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. 

 63.5 



12.2 



Albumen 

 Carbohydrates 

 Alcoholic extract 

 Ethereal extract 

 Ash 



Lecithin 

 Xanthin 

 Guanin . 

 Adeuin . 



3-2 



II. 2 



0.68 

 0.17 

 o.i4 

 o.o8 



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 : 



Nitrogen per cent. 



Lean 

 beef. 



14-3 



Cow's 

 milk. 



4-4 



Soja 

 beans. 

 6.0 



Kussian 

 wheat. 



3-5 



Micrococcus 

 Truffles, 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 substance 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 + S : 25.38 



The percentage (14.75) f nitrogen found is remarkable, and shows that 

 mycoprotein must have a very different constitution from 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 

 (T.), xanthoproteic acid, whereas mycoprotein does not give this reaction. 



