THE INTESTINES 239 



directed for the most part forward, the remaining two back- 

 ward, and the third includes a pronounced secondary 

 curvature in a lateral direction. 



The first limb of the colon bears three rows of small 

 sacculations, the haustra, separated by three longitudinal 

 muscle-stripes, distinguished as the bands of the colon 

 (taeniae coli). Two of these bands are free, while the third 

 is enclosed by the supporting peritoneum, the mesocolon. 

 The two free bands unite toward the anterior end of the 

 first limb and the third or attached band joins them soon 

 after, so that the second limb has but one row of haustra 

 along most of its extent, this row continuing on to the 

 beginning of the third limb. The modifications described, 

 which are not observed in carnivores, serve to increase 

 the storage capacity of the intestine and the area of its 

 walls and to delay the passage of its contents. 



(6) The transverse colon (colon transversum) is a short seg- 

 ment, beginning forw^ard on the right and crossing the 

 middle line transversely to the left, where it bends sharply 

 backward, and is replaced by the descending colon. 



(c) The descending colon (colon descendens) passes backward 

 to a point in front of the pelvis, where it is replaced, with- 

 out any definite demarcation, by the rectum. 



The descending mesocolon, which connects this portion 

 with the dorsal body-wall, should be noted on account of its 

 relation to the inferior mesenteric artery and sympathetic 

 plexuses. It is connected for a considerable distance with 

 the mesentery of the ascending limb of the duodenum. 



7. Displace the caecum, turning it o\'er to the right side of the 

 animal. Lay out the mesenterial small intestine, so that the 

 mesentery and its blood-vessels are exposed. Remove the 

 lymph glands from about the superior mesenteric artery, first 

 noting their position a short distance from the root of the 

 mesentery. They receive afferent lymphatic vessels from the 

 wall of the intestine, and send off efferent vessels to one another 

 and to the lymphatic trunks. 



