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VETERINARY PHYSIOLOGY 



trate the submucous layer. The mucous membrane contains 

 masses of lymph tissue scattered throughout it. In some 

 places these are massed together and form Feyer's patches, 

 which are largest at the lower part of the small intestine. 



The Large Intestine (fig. 142). — The small intestine enters 

 the proximal end of the large intestine at one side, and the 

 opening is guarded by a fold of mucous membrane and a 

 rincj of muscular fibres which form the ileo-csecal valve. 



jSacc. cccec. 



Fi(}. 145. — Stomach of the Horse to show — R. ces., the oesophageal part ; Fu., 

 the fundus with true gastric glands ; B., pyL, pyloric part. 



Above this opening there is a diverticulum — the caecum- 

 which is very large in herbivora and only vestigial in 

 carnivora. Below the opening of the small intestine is the 

 colon {col). This ends in the short rectum which opens into 

 the anal canal, and this is surroimded by a strong band of 

 muscle — the internal sphincter ani — by which it is com- 

 pressed. An external sphincter ani composed of striped 

 muscular fibres encircles the anal orifice. 



The whole large intestine is lined with columnar epithelium, 

 and is studded with Lieberklihn's follicles, in which the epithe- 

 lium is chiefly mucus-secreting in type. There are no villi. 



