DIGESTIVE APPARATUS. 47 



composed of two coats. The inner is mucous membrane ; the 

 outer is muscular and composed of two sets of fibers. One set 

 encircling the oesophagus and the other placed lengthwise. 



The stomach is located in the anterior portion of the abdom- 

 inal cavity. The horse's stomach, when cut open, shows two 

 distinct portions. The mucous membrane which lines the in- 

 terior on the left side is light colored, firm and tough, like the 

 mucous membrane of the oesophagus of which it is a continu- 

 ation. On the right side of the stomach the mucous membrane 

 is soft and red. The horse's stomach holds about t, j / 2 gallons, 

 and the cow's stomach about 45 gallons. The function of the 

 stomach is to receive food and furnish gastric juice. Stomach of 

 the cow is compound, with four cavities. The first cavity, the 

 paunch, is much the largest and acts as a sort of storage vat. 

 Gastric juice is furnished by glands in right side of horse's stom- 

 ach, and by cow's fourth stomach. Effect of gastric juice is to 

 make proteid matters soluble, which it does by the action of its 

 pepsin ferment which is very active. The quantity of gastric 

 juice used by horse and cow varies from 100 lbs. to 170 lbs. in 

 24 hours. 



The small intestine.— This begins at the stomach, the com- 

 mon opening being guarded by the pyloris, a strong sphincter mus- 

 cle like a purse string. The small intestine is divided into three 

 parts duodenum, jejunum, and ileum. The small intestine is about 

 72 feet long in the horse and 140 feet in the cow, and extends from 

 the stomach to the caecum at which point the large intestine lie- 

 gins. 



The stomach, small and large intestine have the same three 

 coats: inner mucous, middle muscular, and outer serous. 



The mucous coat in the small intestines is thickly studded 

 with villi. Various intestinal glands furnish fluids which assist 

 in digestion. 



The muscular coat is composed of two sets of fillers, those 

 of one set encircling the bowel, and those of the other set are 

 lengthwise for the purpose of producing peristaltic action of the 

 intestines. 



The outer coat is the peritoneum, a serous membrane which 



Digitized by Microsoft® 



