Mammalia: Visceral Systen 



630 



in some whales there are more. In the ox and sheep there are four 

 chambers, specialized in relation to the habit of rumination (Fig. 570). 



Intestine 



The digestive tube posterior to the stomach is divided into a longer 

 anterior ("small") intestine and a shorter posterior ("large") intestine. 

 In each of these, differentiated regions may be recognized. Depending 



NASAL PHARYNX 



Fig. 185. Diagram of the human ali- 

 mentary canal. Ventral view. (Courtesy, 

 Jackson: "Morris' Human Anatomy," 

 Philadelphia, The Blakiston Company.) 



on differences in its glandular and absorbing structures, three regions 

 of the anterior intestine may be distinguished — a duodenum adjoin- 

 ing the pylorus, a middle jejunum, and a posterior ileum. In the 

 comparatively short "large" intestine, an anterior region, the colon, 

 is marked by greater diameter and by walls which are sacculated — i.e., 

 having many close-set, outward-bulging, shallow pockets arranged in 

 longitudinal rows (Fig. 185). The shorter terminal rectum is narrower 

 and not sacculated. 



The passage of intestinal contents from the anterior into the pos- 

 terior intestine is usually controlled by an ileocolic valve consisting 



