780 PHYSIOLOGY OF DIGESTION AND SECRETION. 



of 0.2 per cent. HCl, so that if it is of functional importance in 

 gastric digestion its action, like that of the ptyalin, must be con- 

 fined to the early period of digestion before the contents of the 

 stomach have reached their normal acidity. Regarding the proteins, 

 the practical point of interest is as to how far they are digested dur- 

 ing their stay in the stomach. It seems probable that this question 

 does not admit of a categorical answer — that is, the extent of the 

 digestion varies under different circumstances; with the consist- 

 ency of the food, the duration of its stay in the stomach, etc. In 

 some experiments reported by Tobler it is stated that 48 per cent, 

 of a given amount of protein passed through the pylorus as pep- 

 tones or proteoses, about 20 per cent, entered the intestine un- 

 digested, and 20 to 30 per cent, was absorbed from the stomach. 

 In the liquid material (chyme) forced through the pylorus into 

 the duodenum one may find unchanged proteins, primary or 

 secondary proteoses, peptones, or, possibly, cleavage products be- 

 yond this stage. It is stated, however, that most of the material 

 is in the form of proteoses (London). The true value of peptic 

 digestion is not so much in its own action as in its combined action, 

 with the trypsin, or the trypsin and erepsin found in the intestine. 

 The preliminary digestion in the stomach is important as regards 

 the protein foods from several standpoints: First, in the matter of 

 mechanical preparation of the food and its discharge in convenient 

 quantities easily handled by the duodenum. Second, in the more 

 or less complete hydrolysis to peptones and proteoses, whereby 

 the subsequent action of the proteolytic enzymes of the intestine 

 must be greatly accelerated. Indeed, in some cases this prefimi- 

 nary action of the pepsin-hydrochloric acid may be necessary. 

 Native proteins, such as serum-albumin, are not acted upon 

 by trypsin, but if submitted to pepsin-hydrochloric acid they are 

 quickly digested by this enzyme. These and other facts seem to 

 indicate that the peptic digestion is not so much an end in itself as a 

 preparation for subsequent intestinal digestion. The stomach, 

 therefore, may be removed without a fatal result. Several cases 

 are on record in which the stomach was practically removed by 

 surgical operation, the esophagus being stitched to the duodenum.* 

 The animals did well and seemed perfectly normal, although special 

 precautions were necessary in the matter of feeding. 



Absorption in the Stomach. — In the stomach it is possible that 

 there may be absorption of the following substances: Water, salts; 

 sugars and dextrins that may have been formed in salivary digestion 

 from starch, or that may have been eaten as such ; the proteoses and 

 peptones formed in the peptic digestion of proteins or albiuuinoids. 

 In addition, absorption of soluble or liquid substances — drugs, 



* Ludwig and Ogata, "Archiv f. Physiologie," 1883, p. 89; Carvallo and 

 Pachon, "Archives de physiologie norm, et path.," 1894, p. 106. 



