186 THE PROCESSES OF DIGESTION AND ABSORPTION. 



amino-acids. Kuhne's antipeptone, which represents that portion 

 of the tryptic digestive products which cannot be salted out by am- 

 monium sulphate either in neutral, acid, or alkaline media, but 

 which can be precipitated by absolute alcohol, is no chemical unity. 

 Kutscher has demonstrated in the case of fibrin that antipeptone 

 consists to the extent of 30 per cent, of arginin, lysin, and histidin. 

 In addition he found small amounts of leucin, tyrosin, aspartic acid, 

 and still other bodies which were not identified. 



Peptones, analogous to those which Siegfried has described in 

 the case of peptic digestion, are here also formed. These peptones, 

 according to Siegfried, do not contain the tyrosin group and ener- 

 getically resist the further action of trypsin. In this sense they 

 correspond to Kiihne's concept of antipeptone. From fibrin he 

 obtained two bodies of this order, which he terms a- and /9-trypsin- 

 fibrin peptone, C 10 H ir N 3 O 5 and C U H 19 N 3 O 5 . They are both active 

 acids ; they color blue litmus paper red and decompose carbonates 

 with the formation of CO 2 . On decomposition with acids they 

 yield among other products arginin, lysin, glutaminic acid, and 

 possibly also serin. 



From glutin Siegfried obtained a glutin-trypsin-peptone, 

 C 19 H 30 N 6 O 9 . On hydrolysis this in turn yielded a basic peptone 

 which he terms glutolcyrin (TO xupoz, the nucleus), and which on 

 further cleavage yields arginin, lysin, glutaminic acid, and probably 

 glycocoll. He supposes that the kyrin molecule consists of one 

 molecule of arginin, one molecule of lysin, one of glutaminic acid, 

 and two of glycocoll. 



In this connection it is interesting to note that on tryptic digestion 

 of various albumins E. Fischer and Abderhalden obtained a poly- 

 peptid which was resistant to further decomposition by means of 

 trypsin, but which yielded a large amount of -pyrrolidin-carbonic 

 acid and phenyl-alanin on hydrolysis with boiling hydrochloric 

 acid ; this polypeptid no longer gave the biuret reaction. This re- 

 action, indeed, disappears altogether on long-continued tryptic diges- 

 tion, from which we can conclude that Siegfried's peptones also 

 must have undergone further cleavage. No doubt they represent 

 relatively complex polypeptids in the sense of Fischer. 



The end-products of tryptic digestion are, as already pointed out, 

 qualitatively the same as those which result on peptic digestion, with 

 the exception of tryptophan skatol-amino-acetic acid which may 

 in a measure be regarded as characteristic of tryptic action. The 

 essential difference is a matter of velocity of reaction ; this is materi- 

 ally greater with trypsin than with pepsin. 



The chyme from the stomach reaches the duodenum at the begin- 

 ning of the fourth hour after a full meal ; the height of pancreatic 

 digestion lies between the third and the fifth hour. 



In the account of the process of albuminous digestion, as out- 

 lined in the foregoing pages, it has in a manner been assumed that 



