DIGESTION 307 



this point there are any essential differences between the 

 action of trypsin and pepsin.* In both cases the action 

 seems to consist in a splitting up of the complex proteid 

 with assumption of water, so that each successive product 

 is further hydrated than the last ; nor is it, as yet at least, 

 possible to point out any radical distinction between 

 the peptone of gastric and the peptone of pancreatic 

 digestion. It is not necessary to suppose that the further 

 splitting up of some of the peptone by trypsin into leucin, 

 tyrosin, etc., is an action differing in kind so much as in 

 degree from that which leads to the formation of peptone 

 both in tryptic and in gastric digestion. Trypsin is a more 

 powerful ferment than pepsin. And when we find, as we 

 are apt to do, that a pancreatic .digest contains less albumose 

 and more peptone than a peptic digest made under similar 

 conditions, we ascribe this not to a peculiar property 

 possessed by the trypsin and lacking in the pepsin, but to 

 a more energetic action of the former along the common 

 lines. So when this action suffices to push the peptone still 

 farther along the downward path, it is not necessary to 

 assume that an influence radically different from that of 

 pepsin is at work. This argument is strengthened when we 

 find that without a ferment at all, by the prolonged action 

 of various agents which cause hydration (dilute acids or 

 alkalies, or superheated steam, or oxidizing substances like 

 ozone), albumoses and peptones first, and ultimately leucin 

 and tyrosin, may be formed from ordinary proteids. In fact, 

 it would seem that when the complex proteid molecule is 

 split up by proteolytic ferments, or by other and not too 

 violent agents, there are. certain favourite ' sets ' or combina- 

 tions into which its constituents are apt to fall, no matter 

 how the decomposition may be brought about, bodies of the 

 fatty and of the aromatic series being especially constant and 

 conspicuous among the products. Leucin, C 6 H n (NH2)O 2 , 

 for instance, is amido-caproic acid, in which amidogen (NH 2 ) 

 has replaced one H in caproic acid (C 6 H 12 O 2 ), one of the 



* It is scarcely a fundamental distinction that in a peptic digest several 

 albumoses (proto-, hetero-, and deutero-albumose) may be found, and in 

 a tryptic digest only deutero albumose ; for the other albumoses are 

 readily converted into deutero-albumose. 



20 2 



