230 OF DIGESTION. 



(B) It was once imagined that fermentation, and once that 

 trituration, was the cause of digestion, but as neither can produce 

 the same effects on food out of the body that occur in the stomach, 

 these opinions fell to the ground. Besides, no signs of fermen- 

 tation appear when digestion is perfect, and food defended from 

 trituration by being swallowed in metallic balls perforated to 

 admit the gastric juice, is readily digested. 



(C) The digestive process does not go on equally through 

 the whole mass of food, but takes place chiefly where it is 

 in contact with the stomach, and proceeds gradually from the 

 superficies to the centre of the mass, so that the food at the 

 centre is entirely different in appearance from that at the 

 surface, and as soon as a portion is reduced to a homogeneous 

 consistence, it passes into the duodenum without waiting till the 

 same change has pervaded the whole.* 



The cardiac portion of the stomach is the chief seat of the 

 process, and when a part of the food is tolerably digested it 

 passes along the large curvature to the pyloric portion, where 

 the process is completed. As the cardiac half is the great di- 

 gesting portion, it is this half that is found dissolved by the gas- 

 tric juice ; its contents are much more fluid than those of 

 the pyloric half j and Dr. Philip, who by the dissection of about 

 a hundred and thirty rabbits has been enabled to furnish the 

 completest account of what goes on the stomach, relates the 

 case of a woman who had eaten and properly digested to the 

 last, but whose stomach was ulcerated every where except at the 

 cardiac end. Sir Everard Home found that fluids which had been 

 drunk were chiefly contained in the cardiac portion, and that, if 

 the body was examined early after death, the two portions of the 

 stomach were frequently in fact divided by a muscular contrac- 



* Dr. Front, in Thomson's Annals of Philosophy. 1819. 

 Dr. Wilson Philip, An experimental Inquiry info the laivs of the vital func- 

 tions, ffc. 1817. 



