DIGESTION 



railed tin si K.US coat, \\hich adheres closely to it, ami which 

 is continuous with the mesentery ami so with the peritoneum in 

 the way already described. The mucous membrane of the 

 small intestine is thrown into folds. These, however, are unlike 

 the folds of the empty stomach spoken of above, since they arc 

 present ulu n the intestine is full as well as when empty ; 

 moreover, the folds of the mucous membrane of the small 



Kii.. (15. Diagram to .show tin. structure of the wall of llie small intestine. 



. , Villi, and^, nl.imls of the mucous membrane ; c.m, circular muscle layer; 



fin, longitudinal muscle layer ; /, |>ci itoneum, or serous coat. 



intestine arc deeper, more numerous, and lie across the length 

 of the intestine. They are called valvulse conniventes. 

 The mucous membrane, which is lined internally by an epi- 

 thelium, consisting of a single layer of cylindrical cells, is made 

 up of a number of simple tubular glands closely packed 

 loyelher and opening into the cavity of the intestine and of 



