180 



MANUAL, OF PHYSIOLOGY. 



FIG. 79. 



the intestinal juice, by which 

 is meant the fluid poured out 

 by the innumerable short tubes 

 or follicles of Lieberkiihu. 



These intestinal follicles be- 

 long to a very simple form of 

 gland, each one being a single 

 straight depression in the 

 mucous membrane not deep 

 enough to deserve the name 

 of a tube. In the small intes- 

 tine they are set as closely as 

 the villi permit. In the large 

 intestine, where the villi are 

 absent, they are more closely 

 set and are also deeper (Fig. 

 78). They are bounded by 

 a thin basement membrane 

 which is embraced by a close 

 capillary network of blood- 

 vessels, and are lined by a 

 single layer of cylindrical or 

 spherical epithelial cells. 



The epithelial covering of 

 the processes known as villi, 

 which are studded all over the 

 mucous membrane of the small 

 intestine, produce some mucus. 



Method of Obtaining 

 Intestinal Secretion. 



Considerable difficulty has 

 been found in obtaining the 

 proper intestinal juice free 

 from admixture with the secre- 

 tions of the liver and pancreas 



which are carried along and 

 VilhiH with the capillaries injected . . , . A , 



mixed with it. A short por- 

 showing their close relation to epithe- 

 lium, some of the cells of which aredis- tion of the small intestine has, 

 tended with mucus. (Cadiat.) however, been successfully iso- 



