The Digestive System. 



83 



ascending, transverse, and descending parts, that is to say the 

 ascending colon lies on the right side of the body and passes in a 

 general way from its point of origin on the caecum forward to a 

 point where it becomes flexed to the left as the transverse colon; 

 the latter crosses the body and is flexed backward as the descend- 

 ing colon. In the rabbit, however, that portion definable as the 



Fig. 43. The caecum and vermiform process: c', c", z'" , first, 

 second, and third limbs of the caecum; ca, beginning of the ascend- 

 ing colon; il, ileum; pv, vermiform process (appendix) ; sr, sacculus 

 rotundus. 



ascending colon is greatly elongated,' and is composed of five 

 principal limbs, united by flexures. Two of these, in dissection 

 from the ventral surface, are concealed by the base of the superior 

 mesenteric artery, since they lie on its right side. The descending 

 colon is also only nominally related to the left side of the body wall, 

 its supporting peritoneum, the descending mesocolon, being closely 

 connected with the mesoduodenum of the ascending limb of the 

 duodenal loop. The course of the caecum (Fig. 43) as it lies in 

 the body is comparable to two turns of a left-hand spiral, its blind 



