162 LECTURE IV. 



frequently take place; for when persons 

 die of disease, the gastric fluids have not 

 for a long time been prepared, or they have 

 been of an unhealthy quality, so that they 

 are incompetent to dissolve the smallest 

 quantity of the most digestible food, if 

 taken into the stomach. Mr. Hunter could 

 never wonder that the gastric fluids did not 

 act upon the living stomach, for he full well 

 knew that life was a chemist which regu- 

 lated its own chemical operations, and con- 

 trolled the effect of foreign chemical agency. 

 He was, I believe, the first who plainly told 

 the public, that chemical agents do not in 

 general act upon living, as they do upon 

 dead animal matter. He knew that worms 

 live in the stomach, and yet that a meal of 

 dead worms would form no innutritive re- 

 past to an hungry dog. He must have known 

 also that the peculiar fluid which digests the 

 food is not secreted at all times, but only 

 when the stomach is excited by the stimu- 

 lus of food, and even then but under favour- 

 ing circumstances. If in this state persons 

 are suddenly killed by accident, the gastric 

 fluids will continue for some time to act. 



