282 DIGESTION. 



takes place with much more rapidity than is consistent with 

 the gradual permeating and solvent action of any of the 

 digestive fluids. These fluids could not long remain in con 

 tact with the vascular tissues, but would be carried away in 

 the torrent of the circulation. The digestion of parts of a 

 living cold-blooded animal, in which the processes of nutri- 

 tion are very slow, or slightly vascular parts of a warm- 

 blooded animal, is not inconsistent with this supposition. 1 



Circumstances which influence Stomach-Digestion. 



The various conditions which influence stomach-diges- 

 tion, except those which relate exclusively to the character 

 or the quantity of food, operate mainly by influencing the 

 quantity and quality of the gastric juice. It is seldom, if 

 ever, that temperature has any influence ; for the tempera- 

 ture of the stomach in health does not present variations 

 sufficient to have any marked effect on digestion. Ex- 

 periments in artificial digestion have shown that aliment- 

 ary substances are most vigorously acted upon when main- 

 tained in contact with gastric juice at or near 100 Fahr. 



As a rule, gentle exercise, conjoined with repose or 

 agreeable and tranquil occupation of the mind, is more 

 favorable to digestion than absolute rest. Yiolent exercise 

 or severe mental or physical exertion is always undesirable 

 immediately after the ingestion of a large quantity of food, 

 and, as a matter of common experience, has been found to 

 retard digestion. These facts have also been experiment- 

 ally demonstrated by Beaumont in the case of St. Martin. 2 

 Sleep, if light and taken in the sitting posture, seems almost 

 necessary to easy digestion in many persons ; but it should 

 be continued for only a few minutes. A prolonged and deep 



1 If gastric juice be injected under the skin of a living animal, as was done 

 by Bernard (op. cit., p. 407), solution of the areolar tissue, which is non-vascular, 

 and in which the nutritive processes possess very little activity, takes place, and 

 the more vascular and highly organized parts are not attacked. 



2 Op. tit., p. 94. 



