THE LARGE INTESTINE. 309 



ing up in the middle of it, extends nearly to the tip, where 

 it ends commonly by a closed and somewhat dilated ex- 

 tremity. In the larger villi there may be two small lacteal 

 vessels which end by a loop (fig. 8l), or the lacteals may 

 form a kind of network in the villus. The last method 

 of ending, however, is rarely or never seen in the human 

 subject, although common in some of the lower animals 

 (A, fig. 81). 



The office of the villi is the absorption of chyle from the 

 completely digested food in the intestine. The mode in 

 which they effect this will be considered in the chapter on 

 ABSORPTION. 



Structure of the Large Intestine. 



The large intestine, which in an adult is from about 4 to 

 6 feet long, is subdivided for descriptive purposes into three 

 portions, viz. : The cacum, a short wide pouch, commu- 

 nicating with the lower end of the small intestine through 

 an opening, guarded by the ileo-ccecal valve; the colon, 

 continuous with the caecum, which forms the principal 

 part of the large intestine, and is divided into an ascend- 

 ing, transverse and descending portion ; and the rectum, 

 which, after dilating at its lower part, again contracts, 

 and immediately afterwards opens externally through the 

 anus. Attached to the caecum is the small appendix 

 vermiformis. 



Like the small intestine, the large is constructed of three 

 principal coats, viz., the serous, muscular, and mucous. 

 The serous coat need not be here particularly described. 

 Connected with it are the small processes of peritoneum 

 containing fat, called appendices epiplolca. The fibres of 

 the muscular coat, like those of the small intestine, are 

 arranged in two layers the outer longitudinally, the 

 inner circularly. In the ceecum and colon, the longi- 

 tudinal fibres, besides being, as in the small intestine, 

 thinly disposed in all parts of the wall of the bowel, are 



