22 BIOLOGY AND TECHNIQUE 



tions in the percentage of these substances, depending upon the 

 nature of the culture media. Thus, 80 to 90 per cent is water, and 

 in the dry residue, the protein content, estimated from the total 

 nitrogen, varies roughly from 50 to 80 per cent. Cramer 23 has 

 shown that the cholera vibrio, grown on bouillon, contains 69 per 

 cent of protein and 26 per cent of ash, while on Uschinsky's medium 

 the same organism contained only 36 per cent protein, and 14 per 

 cent of ash. It seems probable that such variations may depend to 

 some degree on the semi-permeable nature of the bacterial cell ; and 

 perhaps to an equal degree on the fact that analyses of the mass 

 cultures necessarily include any insoluble metabolic products, such 

 as pigments, the production of which is known to vary with the 

 nature of the media. 



Analyses made by Kappes 24 of B. prodigiosus, and by Nencki 

 and Scheffer 25 of some of the putrefactive bacteria, may serve to 

 illustrate the approximate proportions of the substances making up 

 the bacterial body. The protein is calculated from the total nitro- 

 gen, and since the nucleic acid of the cell is not taken into account 

 the results are not accurate. 



B. Putrefactive 



prodigiosus Bacteria 



Water 85.45 per cent. 83.42 per cent. 



Proteins 10.33 " " 13.96 " " 



Fats 0.7 " " 1. " " 



Ash 1.75 " " 0.78 " " 



Residue 1.77 " " 0.84 " " 



The bacterial protein is probably of several types. A true glob- 

 ulin has been described, and coagulable proteins have been demon- 

 strated by Buchner 26 in the "Pressaft" or juice obtained by sub- 

 jecting bacteria to mechanical pressure. The presence of nuclear 

 material, chromatin, in bacteria, as shown by staining reactions, 

 together with general biological considerations, indicate that some, 

 at least, of the protein is probably combined with nucleic acid in 

 the form of "nucleins" or "nucleoproteins. " The presence of these 



23 Cramer, Arch. f. Hyg., xxii, 1895, 1(57. 



24 Kappes, Analyse der Mossonkulturon, etc., Diss., Leipzig, 1889. 



* Nencld and Scheffer, Jour. f. prakt. Chemie, new series, xix, 1880. 

 26 Buchner, Munch, med. Woch., xliv, 1897, 299. 



