PROTEOSES AND PEPTONES. 135 



is rather generally admitted that they are formed by a synthesis. Accord- 

 ing to SAWJALOW a plastein is not formed from a proteose alone, but 

 always from a mixture of these. LAWROW claims that they may be 

 produced from proteoses as well as from polypeptide substances, and cor- 

 respondingly we must differentiate between the coaguloses or coaguloso- 

 gens from the proteose group coaproteoses, and from the polypeptide 

 group or coapeptides. The latter yield on hydrolysis chiefly monamino- 

 acids while the first yield also basic nitrogenous products. Perhaps 

 the plasteinogen investigated by BAYER/ which essentially differs from 

 the true proteid in its elementary composition as well as from other 

 coaguloses, belongs to the coapeptides. 



The different behavior on saturating their solution with ammonium 

 sulphate has been generally used, as above remarked, for years to dif- 

 ferentiate between the proteoses and peptones. Those precipitable 

 by this salt were called proteoses, and those not were called peptones. 

 This method of division, which never had sufficient support and which 

 was perfectly arbitrary, cannot be considered at the present time. We 

 know now, thanks to the works of EMIL FISCHER and his co-workers, 

 that there are polypeptides either prepared artificially or found among 

 the cleavage products of the proteins, which are precipitated by ammonium 

 sulphate. At the present it is generally conceded that the peptones in 

 the ordinary sense are only a mixture of different bodies. The chief 

 step in these investigations must be the isolation from this mixture 

 of unit bodies with definite chemical characteristics. Of such bodies, 

 besides the polypeptides previously mentioned and studied by FISCHER 

 and others, we must .mention the products isolated by SIEGFRIED and 

 his pupils. 2 



These so-called peptones are in part peptic-peptones and partly 

 tryptic -peptones, and some are prepared from proteid (fibrin) and others 

 from gelatin. The tryptic fibrin-peptones are antipeptones in KUHNE'S 

 sense because they are very resistant to the further action of trypsin. 

 They are according to NEUMANN simultaneously bibasic acids and mono- 

 acidic bases. They give the biuret reaction, but not MILLON'S reaction; 

 they contain no tyrosine and yield on hydrolysis, arginine, lysine, glutamic 

 acid, and it seems also aspartic acid. A peptic-glutin peptone isolated 

 by SIEFGRIED and SCHEERMESSER yielded arginine, lysine, glutamic 

 acid and glycocoll. SIEGFRIED has given proof in several ways as to 

 the purity and unity of the peptones isolated by him. 



1 Hofmeister's Beitrage, 4; see also L. Rosenfeld, ibid., 9; J. Lukomnik, ibid., 9 

 and F. Micheli, Biochem. Centralbl., 6, p. 562. 



2 The works of Siegfried and his pupils, Fr. Miiller, Borkel, Miihler, Kriiger, Scheer- 

 messer and Neumann may be found in Arch. f. (Anat. u.) Physiol., 1894 and Zeitschr. f . 

 physiol. Chem., 21, 41, 43, 45, 48 and 50. 



