182 THE PROCESSES OF DIGESTION AND RESORPTION. 



gestion, moreover, is far more extensive than peptic digestion, so 

 that we may well conclude that the latter essentially represents a 

 preliminary phase of digestion ; and that the digestion proper, viz., 

 the transformation of the albumins into those final products which 

 can be directly utilized by the body in its tissue metabolism, occurs 

 under the influence of the trypsin of the pancreatic juice. 



For convenience 7 sake, we shall study the action of the gastric 

 juice and of the pancreatic juice separately upon the various classes 

 of albumins, as the digestive products which are formed are some- 

 what different in the different classes. In every case we shall follow 

 the fate of these various substances to the final products, as we ob- 

 tain them artificially in digestive experiments in vitro ; but we must 

 bear in mind that such experiments cannot reproduce what actually 

 takes place in the living body, where resorption is constantly going 

 on, and where the various digestive processes in a manner supple- 

 ment each other and conditions overlap. 



Digestion of the Native Albumins. 



Gastric Digestion. In the stomach the native albumins, if in- 

 troduced in the coagulated state, are first transformed into a soluble 

 form, and at the same time or immediately following their dissolu- 

 tion they undergo the process of denaturization i. e., they are trans- 

 formed into syntonins or acid albumins, and as a consequence all 

 individual characteristics which previously existed are lost. This 

 transformation is essentially referable to the hydrochloric acid of the 

 gastric juice, and can be brought about artificially in the absence of 

 pepsin. In such an event, however, a higher grade of acidity and a 

 higher temperature are required. The presence of the pepsin ob- 

 viates such a necessity. A possible explanation of this phenomenon 

 is afforded by the modern doctrine which teaches that the action of 

 enzymes merely consists in hastening the rapidity of reaction. 



On continued exposure to the acid gastric juice albumoses appear 

 and finally peptids ; amino-acids, however, cannot be demonstrated 

 under normal conditions. 



This decomposition may be compared to the inversion of the 

 polysaccharides to monosaccharicles. Kiihne and his school, who 

 have largely contributed to our knowledge of the products of diges- 

 tion, have suggested their division into two classes, viz., the primary 

 and secondary albumoses, according to their nearer or more distant 

 relationship to the original albumins. He recognized two primary 

 albumoses, viz., proto-albumose and hetero-albumose, each of which 

 on further digestion was supposed to give rise to a deutero-albumose, 

 from which in turn peptone was derived. This peptone, which re- 

 sulted from peptic digestion, was regarded as a unity and termed 

 amphopeptone. In it the hemi- and anti-complex of the albuminous 

 molecule were still supposedly united. In a general way this con- 

 cept of the course of peptic digestion has proved correct, but it has 



