ACTION OF THE GASTBIC JUICE UPON THE STOMACH. 279 



ment that the mucous membrane may be dissected from a 

 portion of the stomach of a living animal, and the organ re- 

 turned to its place, and yet secretion of gastric juice and di- 

 gestion of food take place as usual, without the denuded 

 portion being acted upon. 1 



An explanation recently offered by Pavy is exceedingly 

 ingenious; and the experiments by which it is supported 

 demonstrate one of the conditions of highly organized living 

 parts which is inconsistent with the digestive action of the 

 gastric juice. It is well known that acidity is a condition 

 indispensable to the action of the gastric juice upon any prin- 

 ciple or tissue ; and so long as the mucous membrane lining 

 the stomach is abundantly supplied with a constantly chan- 

 ging current of blood, which is distinctly alkaline in its 

 reaction, it is impossible for the gastric juice to have any 

 effect upon it. The immense vascularity of the lining mem- 

 brane of the stomach, particularly during digestion, is in 

 itself almost a sufficient argument in favor of this explana- 

 tion. A tissue thus permeated w r ith an alkaline fluid, which 

 can never be neutralized during life, because it is constantly 

 changing, cannot be digested by the gastric juice. It is difficult 

 to support this view with experiments which are not open to 

 objection and, undoubtedly, the strongest arguments in favor 

 of it lie in the known conditions necessary to digestion in the 

 stomach. In the case of the legs of the frog and the ear of 

 the rabbit, which were digested in the stomach of the dog 

 while the circulation in the parts was not interrupted, the 

 quantity of blood, in the first instance, is so small, and the 

 circulation so languid, that it could readily be neutralized ; 

 and ' the vascularity of the ear, in the second instance, is so 

 slight, that it can easily be conceived to be inadequate to 

 the protection of the tissues. Pavy has shown that the stom- 

 ach is digested during life in rabbits after the application of 

 ligatures at the cardiac and pyloric extremities, the supply 

 of blood being further cut off by ligatures applied to the 

 1 Op. dt., p. 163. 



