INTESTINAL DIGESTION 



8l 



from -^g to I of an inch in thickness. It is covered with 

 peritoneum and lined with mucous membrane. Its muscle 

 fibers extend both lengthwise and circularly. In the mucous 

 membrane of the small intestine are folds, each of which 



Villi (X2oo). 



a epithelium upon the surface of the villi. 



b connective tissue fibers which support the blood tubes and lacteals. 

 c connective tissue cells. 

 d glands which form the intestinal juice. 

 e intestinal gland cut across. 



extends from one half to three fourths the way around the 

 intestine. The folds are called valvulce conniventes. Upon 

 the surface of each fold are finger-like projections called 

 villi, which are from -^ to \ of an inch in length, and 

 from 2-^-3- to y\j- of an inch in diameter. Between the bases 

 of the villi minute tubes, ^o" ^ an ^ nc ^ * n l en gth and 



OV. PHYSIOL. 6 



