BACTERIAL PROTEIDS. 19 



with a clear understanding that it is not free from criticism 

 we may employ it until a more thorough and scientific study 

 of these bodies has been made. 



The difficulty in discussing these substances lies not only 

 in the classification, but in the name which shall be em- 

 ployed to designate them. Briegbr and FrInkel have 

 proposed the term " toxalbumins ;" but, while it is true 

 that some belong to the albumins, others are more truly 

 albumoses ; others are most closely related to the peptones ; 

 and still others diifer in some important respects from all 

 of these. In view of the above facts, we have decided upon 

 the ter;n " bacterial proteids " to designate those formed by 

 the fermentative action of germs, while those which consti- 

 tute an integral part of the cell will be known as "the 

 bacterial cellular proteids." 



The Bacterial Cellular Proteids. — ^Nencki first prepared 

 one of these substances from putrefactive bacteria. These 

 were obtained by decantation, freed from fat with ether, 

 dissolved in fifty parts of a potash solution of 0.6 per cent., 

 heated for some hours at 100° and filtered. The filtrate 

 was acidified with dilute hydrochloric acid and precipitated 

 by the addition of rock salt. The precipitate was washed 

 with a saturated salt solution, dried at 100°, and washed 

 free from salt with water. Nencki designates this sul)- 

 stance as " mycoproteiu," and finds that it has the formula, 

 C25H42N50g. Freshly precipitated mycoprotein forms in 

 amorphous flakes, which are soluble in water, alkalies, and 

 acids. The aqueous solution is acid in reaction. After 

 being dried at 100° it is no longer wholly soluble in water. 

 Nencki found that it is not precipitated from aqueous solu- 

 tion by alcohol, but by picric acid, tannic acid, and mercuric 

 chloride; that it does not give the xanthoproteid, but 

 does give the Millon and the biuret reactions. According 

 to ScHAFFER it is changed by acids into peptone, and on 

 being ftised with five parts of potash it breaks up into am- 

 monia, amylamin, phenol (0.16 per cent, of its weight), vale- 

 rianic acid (38 per cent.), leucine, and traces of indol and 

 skatol. A proteid obtained from the yeast plant has the 

 formula, Ci2H2iN^303. 



