DIGESTION IN SMALL INTESTINE. 339 



chiefly in the greatly increased quantity of fat particles 

 which have been absorbed from the small intestine. 



Although the most evident function of the small intes- 

 tine is the digestion of fat, it must not be forgotten that 

 a great part of the other constituents of the food is by no 

 means completely digested when it leaves the stomach. 

 Indeed, its leaving it unabsorbed would, alone, be proof of 

 this fact. 



The albuminous substances which have been partly dis- 

 solved in the stomach continue to be acted on by the 

 gastric juice which passes into the duodenum with them, 

 and the effect of the last-named secretion is assisted or 

 complemented by that of the pancreas and intestinal 

 glands. As the albuminous matters are dissolved, they 

 are absorbed chiefly by the blood-vessels, and only to a 

 small extent, probably, by the lacteals. 



The starchy, or amylaceous portion of the food, the con- 

 version of which into dextrin and sugar was more or less 

 interrupted during its stay in the stomach, is now acted 

 on briskly by the secretion of the pancreas, and of Brunn's 

 glands, and porhaps of Lieberkuhn's glands also, and the 

 sugar as it is formed dissolves in the intestinal fluids, and 

 afterwards, like the albumen, is absorbed chiefly by the 

 blood-vessels. 



The liquids, swallowed as such, which may have escaped 

 absorption in the stomach, are absorbed probably very 

 soon after their entrance into the intestine j the fluidity of 

 the contents of the latter being preserved more by the con- 

 stant secretion of fluid by the intestinal glands, pancreas, 

 and liver, than by any given portion of fluid, whether 

 swallowed or secreted, remaining long unabsorbed. From 

 this fact, therefore, it may be gathered that there is a 

 kind of circulation constantly proceeding from the intestines 

 into the blood, and from the blood into the intestines 

 again ; for, as all the fluid, probably a very large amount, 

 secreted by the intestinal glands, must come from the 



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