STOMACHAL DIGESTION. 



233 



omphalo-mesenteric vein (later becoming the portal vein). 

 The liver is thus formed by the junction of two organs: first, 

 the biliary liver, formed of tubes 

 lined with a columnar epitheli- 

 um, such as the glands of Lieber- 

 kiihn ; and, second, the blood 

 liver, constituted by the real acini 

 of the liver (around which are 

 placed the biliary culs-de-sac) ; 

 the purpose of these is to elabo- 

 rate the blood, and especially to 

 introduce into it sugar or glyco- 

 genous matter; whence the name 

 of glycogenic liver, though the 

 presence of sugar is not peculiar 

 to the tissue of the liver. 



These different glands pour 

 into the intestinal tube their 

 secretory products, which thus 

 come generally in contact with 

 the alimentary substances re- 

 ceived from without: these sub- 

 stances are modified by the fluids, 



and at the same time subjected Fig. ^-^ 8 of 

 to phenomena of. transportation 

 (peristaltic movements) by means of the muscular coats of 

 the stomach and intestines. We shall study these chemical 

 and mechanical phenomena in the stomach and in the intes- 

 tine, and shall see how the larger portion of the substances 

 which are thus elaborated is absorbed by the coats of the 

 digestive tube, and especially by its epithelium; and also, 

 finally, how the residuum of the aliments, as well as the prod- 

 ucts of intestinal desquamation, are rejected after passing 

 through the large intestine. 



A. Stomach. 



The stomach is a pouch, intended as a temporary receptacle 

 for the aliments introduced into it by the act of deglutition. 

 Some aliments only pass through the stomach, such as, in 

 horses especially, those fluids which accumulate in the intes- 



* rr, Thick layer of glands. 6, Tissue belonging to the mucous and the cel- 

 lular layer, c, Sub-inucous tissue traversed by the vessels cut transversely. </, 

 Layer of the circular muscular fibres, e, Longitudinal fibres. J, Peritoneal en- 

 velope. (Kolliker, " Ilistologie.") 



