210 DIGESTION. [CHAP. xxiv. 



artificial digestion, that, by gently shaking the tubes in which the 

 process of digestion was going on, it became accelerated. This 

 accords with what daily experience points out to us, namely, that 

 agreeable and lively conversation during a meal, or gentle exercise 

 after one, invariably promotes the primary stages of digestion. 



Violent exercise after meals retards digestion, most probably by 

 preventing the constant action of the gastric fluid upon the pieces 

 of food in it the movements of the body causing frequent change 

 of place in the morsels of food. 



The use of alcoholic stimulants also retards digestion, by coagu- 

 lating the pepsine, and thereby interfering with its action. Were 

 it not that wine and spirits are rapidly absorbed ; the introduction 

 of them into the stomach in any quantity would be a complete bar 

 to the solution of the food, as the pepsine would be precipitated 

 from solution as quickly as it was secreted by the stomach. 



Absorption by the Stomach. An important question, to which 

 as yet we can give no certain reply, is as to what becomes of the 

 food after it has been duly dissolved by the fluids of the stomach. 

 When we find how completely albuminous and fibrinous substances 

 are dissolved by digestion in the natural or artificial gastric fluid, it 

 cannot be doubted that they are in a state fit for absorption while 

 yet in the stomach, nor can there be any good reason to deny that a 

 considerable quantity must be absorbed without passing further on 

 in the alimentary canal. The great rapidity with which liquids of 

 a simple and limpid kind, or the aqueous solutions of certain salts, 

 as iodide of potassium, the alkaline carbonates, etc., find their way 

 into the blood, denotes that this must take place very quickly after 

 they have been swallowed, and that the blood-vessels of the stomach 

 must be the principal channel through which they effect their 

 entrance into the circulating system, and it scarcely admits of doubt 

 that the dissolved aliments are removed through the same channels.*" 



The venous blood of the stomach passes to the vena portse. 

 Hence, matters absorbed by the sanguiferous system of the stomach 

 pass by a very direct route to the liver, and probably excite that 

 gland to increased secretion for the purposes of digestion in the 

 small intestine. 



The gastric fluid dissolves perfectly only the fibrinous and albumi- 

 nous animal substances, and probably also the glutinous or azotised 

 portion of vegetable food ; we must suppose, therefore, that it is only 



* We have detected iodine in the saliva and urine in twenty minutes after 

 a solution of a few grains of iodide of potassium in a large quantity of water 

 had been swallowed. 



