ARTIFICIAL DIGESTION. 285 



the digestion, which had already commenced, by means of 

 artificial heat in a water- bath. In a few hours the food 

 thus treated was completely chymified ; and the artificial 

 seemed in this, as in several other experiments, to be 

 exactly similar to, though a little slower than, the natural 

 digestion. 



The apparent identity of the process in- and outside 'of 

 the stomach thus manifested, while it shows that we may 

 regard digestion as essentially a chemical process, when 

 once the gastric fluid is formed, justifies the belief that 

 Dr. Beaumont's other experiments with the digestive fluid 

 may exactly represent the modifications to which, under 

 similar conditions, its action in the stomach would be 

 liable. He found that, if the mixture of food and gastric 

 fluid were exposed to a temperature of 34 F., the process 

 of digestion was completely arrested. In another experi- 

 ment, a piece of meat which had been macerated in water 

 at the temperature of 100 for several days, till it acquired 

 a strong putrid odour, lost, on the addition of some fresh 

 gastric juice, all signs of putrefaction, and soon began to 

 be digested. From other experiments he obtained the 

 data for estimates of the degrees of digestibility of various 

 articles of food, and of the ways in which the digestion is 

 liable to be affected, to which reference will again be 

 made. 



When natural gastric juice cannot be obtained, many 

 of these experiments may be performed with an artificial 

 digestive fluid, the action of which, probably, very closely 

 resembles that of the fluid secreted by the stomach. It is 

 made by macerating in water portions of fresh or recently- 

 dried mucous membrane of the stomach of a pig* or other 

 omnivorous animal, or of the fourth stomach of the calf, 



* The best portion of the stomach of the pig for this purpose is that 

 between the cardiac and pyloric orifices ; the cardiac portion appears to 

 furnish the least active digestive fluid. 



