106 SPECIAL HISTOLOGY. 



a part of which, in all probability, is at once taken up by the 

 internal blood-vessels, while the larger proportion is excreted 

 and absorbed by the lymphatics. The period of their greatest 

 activity (when they become distended) coincides with that of 

 the intestinal absorption, either because they absorb from the 

 intestine or because they simply participate in the greater 

 activity of the intestine at this time ; and perhaps the more 

 albuminous matters which they yield may be connected with 

 the development of cells in the chyle. This hypothesis will 

 hold good in its principal outlines, even if in future the direct 

 connexion of the lymphatics with the follicles, or the occurrence 

 of lacteals within them, should be demonstrated ; at any rate, 

 it will not be blamed for being too wide of the facts.] 



§ 156. 



Mucous membrane of the large intestine. — The structure of 

 the mucous membrane in the large intestine agrees so closely 

 in essentials with that of the small intestine, that it may 

 suffice here to draw attention to a few points only : 



The mucous membrane of the large intestine, if we except the 

 rectum, has no proper folds, for the transversely fibrous muscular 

 layer also enters into the plicae sigmoidece. The villi also are 

 absent, from the edge of the ileo-csecal valve, into which the 

 muscular tunic likewise enters, onwards ; and the mucous sur- 

 face, apart from some occasional, hardly perceptible, small, wart- 

 like elevations, is even and smooth. It is difficult to detect the 

 muscular layer of the mucous membrane in the human colon, 

 though it is unquestionably present ; it is more distinct in the 

 rectum. In animals I find it well developed. According to 

 Briicke, in the colon (of animals ?) its longitudinally and trans- 

 versely fibrous layers, which also exist here, are only 0013'" 

 thick, the diminution having taken place at the expense of the 

 external longitudinal fibres, which are reduced to a three-fold 

 or even only a two-fold stratum ; in the rectum, the layers are 

 again of equal thickness, and, taken together, measure about 

 0022'", at the anus even 0-088'" and more. 



The glandular organs of the large intestine are Lieberkuhn's 

 glands and solitary follicles ; the former, also termed glands of 

 the large intestine, are distributed over its whole surface from the 

 ileo-csecal valve to the anus and in the processus vermicularis. 



