154 ABSORPTION IN THE STOMACH. [BOOK II. 



mechanical movements which aid the chemical action of the gastric 

 juice so efficiently as to enable the stomach to effect digestive opera- 

 tions which, in point of magnitude, cannot be imitated in the labora- 

 tory. 



The term The term Chyme (^u^d?, juice) was formerly gene- 



Chyme ex- rally applied to the pulpy semi-fluid matter resulting 

 plained. f rom the action of the gastric juice on the mixed 



aliments, and the term Chymification to the process which results 

 in the formation of chyme. 



The stomach Doubtless when much fluid is introduced into the 

 abso S tion f s t macn > absorption at once commences actively. This 

 much P ^^ is proved by the fact (amongst others) that almost 

 and of diffu- instantly the sensation of thirst, which depends primarily 

 sibie sub- upon a diminution of the water of the blood, diminishes. 

 stances. _A^ the same time, the absorption of some diffusible 



substances occurs, as is proved by the fact that a few minutes 

 after the introduction of potassium iodide into the stomach, the 

 salt is separated by the kidneys and salivary glands. The extent to 

 which the process of absorption proceeds in the stomach cannot, 

 however, be exactly stated. This subject will be more fully con- 

 sidered in the sequel. 



There is an interesting observation, which has repeatedly been made in 

 dogs with gastric fistulae, which proves both the rapidity with which 

 absorption goes on and the fact that thirst, though a local sensation, is yet 

 but the expression of the genei'al want of the system for water. If in a 

 dog with a gastric fistula, the cannula be allowed to remain unplugged 

 until the animal manifests decided thirst, then on water being given to it, 

 the animal will commence drinking and will continue to drink indefinitely, 

 the water running out through the cannula as fast as it enters the stomach. 

 So soon however as the cannula is plugged, the animal behaves as normal 

 animals do, and, after a very small quantity of fluid has been taken, stops 

 drinking ; in a small fraction of a minute sufficient absorption of water has 

 occurred to relieve the general want for water, of which the sensation 

 of thirst was the local expression. 



The consti- constituents which are chemically acted upon 



tuents of food by the gastric juice in the stomach are firstly the pro- 



which are teids, and secondly the albuminoid bodies, collagen and 



acted upon gelatin, chondrigen and chondrin (?). 

 chemically in ^ Q other groups of organic food constituents, viz. 



the stomach. r . , 111, TI^I ^ i i 



fats and carbohydrates, are very slightly acted upon by 



the gastric juice itself; in considering this slight action of the gastric 

 juice we shall have to enquire to what extent the amylolytic action 

 of the saliva upon the alimentary starch is allowed to proceed in the 

 presence of the acid juices of the stomach. 



