80 DIGESTION, 



of a true peristaltic motion in the stomach during health, is, 

 however, not quite certain ; indeed, the undulatory agitation of 

 the stomach that occurs, appears intended for the purpose of 

 driving the thoroughly dissolved portions downwards, while those 

 portions which are not completely subacted are repelled from the 

 pylorus by an antiperistaltic motion. 



" The other aids commonly enumerated, are the pressure on 

 the stomach from the alternate motion of the abdomen, and the 

 high temperature maintained in the stomach by the quantity of 

 blood in the neighbouring viscera and blood-vessels, which tem- 

 perature was at one time supposed to be of such importance, that 

 the word coction was synonymous with digestion." 



It was once imagined that fermentation, and once that tritur- 

 ation, 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 ferment- 

 ation appear when digestion is perfect; and food, either defended 

 from trituration by being swallowed in metallic spheres perforated 

 to admit the gastric juice P, or immersed in gastric juice out of 

 the body q , is readily digested. 



p The Abbe Spallanzani and Dr. Stevens made such experiments upon brutes : 

 but the latter experimented upon a man also, who was in the habit of swallowing 

 stones and rejecting them, and who of course found no difficulty in doing the 

 same with metallic balls. 



* Experiments of this kind were made by Spallanzani, who procured the 

 gastric juice by causing hungry animals to vomit, or by introducing a sponge 

 into the stomach. But still more marked results were lately obtained in the case 

 of a lad who had a fistulous opening from the stomach, in consequence of a wound 

 through which, by means of a hollow bougie and elastic bottle, gastric juice was 

 procured at pleasure. A portion of beef was introduced into the stomach on a 

 thread and withdrawn for comparison, at the same time that a similar portion was 

 plunged into a phial of gastric juice, the temperature of which was kept steadily 

 in a sand-bath at 100, the degree of the stomach's temperature, ascertained by 

 the introduction of a thermometer. The portion in the phial became completely 

 dissolved, though more slowly than that in the stomach ; probably from the latter 

 being supplied with a succession of fresh gastric juice, and freely exposed to it by 

 motion ; for the action of the fluid is only on the surface, and a portion of chicken 

 placed in a phial of gastric juice, for a similar experiment, was more quickly acted 

 upon if agitated. The gastric juice, when first obtained, was almost as clear as 

 water, and its antiseptic power was shown by the solutions of beef and chicken 

 remaining a whole autumnal month without foetor or sour taste. American Me- 

 dical Recorder, January, 1826. Spallanzani and others found, that if gastric juice 

 is applied to putrescent matter, it removes the fcetor and suspends putrefaction. 



