GASTRIC JUICE, AND STOMACH DIGESTION. 149 



the process of nutrition, a series of catalytic changes, which are 

 characteristic of the vital operations, and which are determined by 

 the organized materials with which they are in contact, and by all 

 the other conditions present in the living organism. These changes, 

 therefore, of nutrition, secretion, &c., necessarily exclude for the 

 time all other catalyses, and take precedence of them. In the same 

 way, any dead organic matter, exposed to warmth, air, and moist- 

 ure, putrefies ; but if immersed in gastric juice, at the same 

 temperature, the putrefactive changes are stopped or altogether 

 prevented, because the catalytic actions, excited by the gastric 

 juice, take precedence of those, which constitute putrefaction. For 

 a similar reason the organic ingredient of the gastric juice, which 

 acts readily on dead animal matter, has no effect on the living 

 tissues of the stomach, because they are already subject to other 

 catalytic influences, which exclude those of digestion, as well as 

 those of putrefaction. As soon as life departs, however, and the 

 peculiar actions taking place in the living tissues come to an end 

 with the stoppage of the circulation, the walls of the stomach are 

 really attacked by the gastric juice remaining in its cavity, and 

 are more or less completely digested and liquefied. In the human 

 subject, it is rare to make an examination of the body twenty-four 

 or thirty-six hours after death, without finding the mucous mem- 

 brane of the great pouch of the stomach more or less softened and 

 disintegrated from this cause. Sometimes the mucous membrane 

 is altogether destroyed, and the submucous cellular layer exposed ; 

 and occasionally, when death has taken place suddenly during 

 active digestion, while the stomach contained an abundance of 

 gastric juice, all the coats of the organ have been found destroyed, 

 and a perforation produced leading into the peritoneal cavity. 

 These post-mortem changes show that, after death, the gastric juice 

 really dissolves the coats of the stomach without difficulty. But 

 during life, the chemical changes of nutrition, which are going on 

 in their tissues, protect them from its influence, and effectually 

 preserve their integrity. 



The secretion of the gastric juice is much influenced by nervous 

 conditions. It was noticed by Dr. Beaumont, in his experiments 

 upon St. Martin, that irritation of the temper, and other moral 

 causes, would frequently diminish or altogether suspend the supply 

 of the gastric fluids. Any febrile action in the system or any 

 unusual fatigue, was liable to exert a similar effect. Every one is 

 aware how readily any mental disturbance, such as anxiety, anger, 



