268 DIGESTION. 



of the fatty constituents of the food are liquefied at the tem- 

 perature of the body ; and when taken in the form of adipose 

 tissue, the little vesicles in which the oleaginous matter is 

 contained are dissolved, the fat is set free and melted, and 

 floats in the form of great drops of oil on the alimentary 

 mass. The action of the stomach, then, seems to be to pre- 

 pare the fats, chiefly by dissolving the adipose vesicles, for 

 the complete digestion which takes place in the small intes- 

 tine. 



Action on Saccharine and Amylaceous Principles. The 

 varieties of sugar of which glucose is the type undergo little, 

 if any, change in digestion, and are probably for the most 

 part directly absorbed by the mucous membrane of the 

 stomach. This is not the case, however, with the varieties 

 of sugar classed with cane-sugar. The experiments of Ber- 

 nard and Barreswil 1 have shown that cane-sugar injected 

 into the veins of a living animal is not assimilated by the 

 system, but is immediately rejected by the kidneys. "When, 

 however, it has been changed into glucose by the action of a 

 dilute acid, or by digestion in the gastric juice, it no longer 

 behaves as a foreign substance, and does not appear in the 

 urine. 



This leads to a consideration of the changes which cane- 

 sugar undergoes in the stomach. Experiments have shown 

 that this variety of sugar, after being digested for several hours 

 in the gastric juice, is slowly converted into glucose. This 

 action, according to the recent observations of Longet and 

 Schiff, does not depend upon any constituent of the gastric 

 juice except the free acid ; and they found that an exceedingly 

 dilute mixture of hydrochloric acid had an equally marked 

 effect. 2 Dalton founcl that, in the dog, the ingestioii of cane- 

 sugar induced, almost invariably, an immediate reflux of 

 intestinal fluids, including bile, by which it was promptly 



1 Loc. cit. 



2 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 221. 



