v INTERNAL EESTITUTIVE SECRETIONS 265 



perceptible amount. Against this, however, we must set the 

 fact that evacuation of the stomach does not occur as rapidly 

 when the duodenal fistula is obstructed, on which the fluid is 

 prevented from escaping to the outside, and is forced into the 

 intestine. This is due, according to von Mering, to the fact that 

 the fluid on filling the small intestine reflexly delays the flow 

 from the stomach, and increases the tone of the pyloric valve. 

 Under these conditions (which correspond to the normal) it is 

 probable that absorption of water by the gastric walls is con- 

 siderable. 



When, instead of plain water, salt solution is introduced into 

 the dog's stomach by the duodenal fistula, the -liquid that flows 

 out of the fistula 'con tains much less salt and much more water. 

 The stomach must, therefore, absorb the salt and excrete the 

 water. After injecting, e.g., 30 grms. of sodium chloride dissolved 

 in 400 c.c. water into the stomach, 6'5 grms. of salt were absorbed, 

 and 787 c.c. of fluid escaped from the fistula. The same fact 

 appears on injecting a solution of glucose into the stomach : part of 

 the sugar is absorbed, and the volume of fluid escaping from the 

 fistula is much increased. 



When solutions of proteose and peptone are injected into the 

 stomach of dogs with a duodenal fistula, the quantity absorbed 

 increases with the concentration of the solutions. In this case, 

 moreover, that part of the water which forms the solvent is 

 absorbed as well as part of the dissolved substances. According 

 to von Mering, the gastric mucous membrane can, under the 

 most favourable conditions, absorb 60 per cent peptone, while it 

 can only absorb 20 per cent sugar. Concentration of peptone 

 solution promotes absorption of water, but the contrary takes 

 place for sugar. 



Considerable influence is exerted upon gastric absorption by 

 substances that excite the epithelium of the stomach, e.g. alcoholic 

 beverages, and the usual condiments and spices. 



Alcohol is entirely absorbed, and greatly assists absorption of 

 the substances dissolved in it. Salt, in the amount that is 

 agreeable to the palate and is commonly used as a condiment 

 (about 2 per cent), also favours absorption, as do also mustard, 

 pepper, nutmeg, ginger, etc. These condiments accordingly not 

 only excite gastric secretion (as is commonly stated), but also 

 facilitate absorption of foods which are naturally soluble or have 

 become soluble by digestion in the stomach either by exciting 

 the absorbing epithelial cells, or by provoking active hyperaemia 

 and improved circulation in the blood and lymph capillaries of 

 the mucous membrane. 



II. The tract best adapted to digestion is undoubtedly the 

 Mucous Membrane of the Gut, especially that of the small intestine, 

 more particularly of the duodenum and jejunum, where there 



