DIGESTION. 261 



situate beneath the blood-vessels. It is without doubt instrumental in 

 the propulsion of chyle along the lacteal. 



The lacteal vessel enters the base of each villus, and passing up in the 

 middle of it, extends nearly to the tip, where it ends commonly by a 

 closed and somewhat dilated extremity. In the larger villi there may be 

 two small lacteal vessels which end by a loop (Fig. 192), 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. 192). 



FIG. 192. A. Villus of sheep. B. Villi of man. (Slightly altered from Teichmann.) 



The office of the villi is the absorption of chyle and other liquids from 

 the intestine. The mode in which they affect this will be considered in 

 the Chapter on ABSORPTION. 



II. 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 (Fig. 165), viz.: the ccecum, 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 ascending, transverse and descending portion; and the rectum, which, 

 after dilating at its lower part, again contracts, and immediately afterward 



