570 THE INTESTINAL CANAL, BY E. KLEIN AND E. VERSON- 



millimeter. The crypts are usually held to consist of a structure- 

 less membrana propria lined by a layer of cylindrical epithelial 

 cells. The latter are identical with those forming the epithe- 

 lium of the intestine generally, and the remarks that have been 

 made respecting these apply to them also. The only slight 

 difference that exists between them is, that the attached ex- 

 tremities of the cells forming the epithelium of the crypts are 

 for the most part broader than the free extremities, which is 

 intelligible when it is remembered that their free surfaces 

 bound a tube of narrower diameter than the cryptic membrane 

 itself. 



In very fine sections of the intestine, from which the epi- 

 thelium has been completely detached by delicate brushing, or 

 where the epithelium is accidentally absent, it may easily be 

 demonstrated that the so-called membrana propria of the crypts 

 is not entirely structureless ; for from the interfollicular trabe- 

 cular tissue a few delicate fibrils penetrate into the basement 

 membrane, and, preserving the longitudinal direction of the 

 'tube, run towards its orifice, near which they become continu- 

 ous with a similar but transversely coursing fibrous tissue ; 

 this on the other hand, like the branches of a tree, is given 

 off at almost right angles from the septal investing sheaths of 

 the follicles. Such membranes moreover exhibit a beautiful 

 rounded-polygonal pattern, corresponding to the bases of the 

 detached epithelial cells. 



The Lieberkiihnian follicles occupy the whole free surface of 

 the intestine, with the exception of the bases of the villi and 

 the surface of the solitary glands. But whilst their orifices 

 must necessarily be separated by the former, the tubes dilate 

 beneath them in such a manner as almost again to come into 

 contact, leaving only small interspaces for the passage of 

 vessels and muscular fasciculi. They are usually altogether 

 absent over the follicles, that is to say, of course, where these 

 project into the lumen of the intestine, and here they are 

 arranged like a coronet around the elevations, which has led to 

 the employment of the term corona tubulorum by Johann 

 Muller. 



MUSCULARIS Mucos^E. Lying between the mucous mem- 



