304 SPLAl^CHNOLOGT. 



tion, where they do not entirely disappear on inflation. The 

 cardiac orifice is closed by the mucous membrane of the oeso- 

 phagus ; its numerous folds completely filling that tube at its 

 termination when empty ; the valve thus formed is air-tight. 



The arteriei^ of the stomach arise from all the branches of the 

 coeliac axis ; they are the gastric, the left gas tro- epiploic from 

 the splenic, and the right gastro-epiploic from the hepatic ; the 

 blood is returned by satellite veins which join the vena porta. 

 The nerves are from the pneumogastric, and solar plexus of the 

 sympathetic. 



The use of the stomach is to macerate the food by the action 

 of its muscular walls, and also to saturate it v/ith mucus and 

 gastric juice, the latter containing a principle called pepsine, 

 which acts chemically on albuminous matters. The entire 

 operation is called chymiflcaiion, and the food thus prepared the 

 chyme. ; ' 



THE INTESTINES. 



These are divided into the large and small ; the two however 

 form a continuous musculo-membranous tube, the small intestine 

 being likewise continuous with the stomach at. its pyloric orifice. 

 These organs are tortuous in their course, and in herbivorous 

 animals are long and capacious. 



SMALL INTESTINE. 



The small intestine commences at the pylorus, and terminates, 

 in the caecum. It consists of a cylindrical convoluted tube, rather 

 more than an inch in diameter, and about seventy-two feet in 

 length. It presents two curvatures, the greater one, convex and 

 free, the lesser concave and attached to the mesentery, by which 

 it is suspended from the roof of the abdomen, occupying the 

 central region, and partly surrounded by the large intestine. It 

 is arbitrarily divided into the Duodenum, the Jejunum, and the 

 Ileum. 



The duodenum, continuous with the pylorus, is the only fixed 

 portion of the small intestine. In the horse it is short, present- 

 ing a dilatation at its origin resembling a miniature stomach, 

 with its curvatures disposed inversely to those of the stomach 

 itself. On leaving the pylorus it runs forwards, then backwards, 

 forming an abrupt curve. It now crosses from right to left, and 



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