166 OF FOOD, AND THE DIGESTIVE PROCESS. 



aginous matters. Although the change in the starchy particles, which com- 

 mences in the mouth, is usually continued in the stomach, yet its continu- 

 ance is essentially dependent upon the presence of the salivary fluid; being 

 materially checked, when, by tying the oesophagus, that fluid is prevented 

 from passing into the stomach. 1 [The experiments by the American editor 

 upon Alexis St. Martin, alluded to in the text on page 156, confirm the 

 statements here made as to the office of the Gastric juice in digesting albu- 

 minous articles of food, by a previous conversion into albuminose or pep- 

 tones. So, also, that Gastric juice has no action upon oleaginous food, other 

 than to liberate the oil by dissolving away the albuminous envelopes of the 

 fat-vesicles. With regard to amylaceous constituents of food, these experi- 

 ments upon St. Martin, as well as others more recently performed, through 

 the kindness of Dr. E. Brown-Sequard, who, it will be remembered, has the 

 faculty of vomiting at will, showed distinctly the presence of grape-sugar in 

 the products of Gastric digestion as determined by Trommer's test; and this 

 in much larger quantity than could be obtained by the action of saliva for 

 the same length of time upon a portion of the same arrowroot swallowed by 

 Brown-Sequard, and which had been previously tested for glucose without 

 the response usual when this substance is present. That the glucose thus 

 found in the products of Gastric digestion is the result of the action of 1 Gas- 

 tric juice upon the amylaceous food is not contended for. The change has 

 been most probably produced by the action of the mucus secreted by the 

 mucous follicles of the stomach, as it is well known that mucus from any of 

 the mucous membranes has this effect. Thus, an injection of starch in the 

 rectum, when evacuated, is found to respond to Trommer's test for grape- 

 gugar.] Its conversion into dextrin and sugar is completed in the small 

 intestine by the action of the gastric juice. The experiments of Dr. Dalton 2 

 on the introduction of the garden snail and slug into the stomachs and gas- 

 tric juice of dogs, show that no living animals, at least of this grade of de- 

 velopment, can long resist the digestive process, death occurring in the 

 course of a few minutes, which is speedily followed by the disappearance of 

 all traces of their bodies. The action of the gastric juice seems essentially 

 to stand in the place of a high temperature and a powerful oxidizing agent; 

 but though albuminous substances are converted into peptones during diges- 

 tion, yet as no peptones are found in the fluids of the body, but simply albu- 

 men, 'this conversion seems to be only accomplished for the purpose of pro- 

 moting its absorption. For, as Prof. Graham has shown, albumen has a 

 very low diffusive power, and a very high eudosmotic equivalent; and 

 although, when subjected to considerable pressure, its solutions will filter 

 slowly through animal membranes (thus affording a rationale of its occa- 

 sional appearance in various transudations), yet it is obvious that unless 

 some such preliminary change took place, a very insufficient supply of this 

 material would gain entrance into the blood. 



117. This action of the gastric solvent upon the azotized constituents of 

 the food, is dependent upon several accessory conditions. One of the most 

 important of these is temperature. A heat of from 9(5 to 100 is required 

 to keep up the solvent process, which is retarded according to the depres- 

 sion of the thermometer below this standard; so that at the ordinary tem- 

 perature of the atmosphere it is completely suspended, to be renewed, how- 

 ever, with an increment of heat. On the other hand, a trifling elevation of 

 temperature above 100 occasions a decomposition in the gastric juice, which 

 entirely destroys its solvent power. The next condition, which specially 



1 Soe Fivridis in Wagner's Handworterbuch, Bd. iii, Art. Vcrdauung. 

 J Amor. Juurn. of Med. Science, April, 1865, p. 304. 



