136 THE PROTEIN SUBSTANCES. 



is rather generally admitted that they are formed by a synthesis, a view 

 which has received support by the investigations of V. HENRIQUES and 

 GjALDBAK. 1 According to SAWJALOW a plastein is not formed from a 

 proteose alone, but always from a mixture of proteoses. LAWKOW claims 

 that they may be produced from proteoses as well as from polypeptide 

 substances, and correspondingly we must differentiate between the coag- 

 uloses or coagulosogens 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 prod- 

 ucts. Perhaps the plasteinogen investigated by BAYER 2 which differs 

 essentially 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 ammo- 

 nium 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. 3 



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 pepsin-glutin peptone isolated 

 by SIEGFRIED and SCHMITZ yielded arginine, lysine, glutamic acid, gly- 



1 Zeitschr. f. physiol. Chem., 71 and 81. 



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

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



3 The works of Siegfried and his pupils, Fr. Miiller, Borkel, Miihle, Kriiger, Scheer- 

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

 Zeitschr. f. physiol. Chem., 21, 41, 43, 45, 48, 50, and 65 and Pfliiger's Arch. 136. 



