THE LARGE IXTESTIXE. 249 



through the anus. Attached to the caecum is the small appen- 

 dix vermiformis. 



Like the small intestine, the large is constructed of three 

 principal coats, viz., the serous, muscular, and mucous. The 

 serous coat need not be here particularly described. Connected 

 with it are the small processes of peritoneum containing fat, 

 called appendices epiploicce. The fibres of the muscular coat, 

 like those of the small intestine, are arranged in two layers 

 the outer longitudinally, the inner circularly. In the caecum 

 and colon, the longitudinal fibres, besides being, as in the small 

 intestine, thinly disposed in all parts of the wall of the bowel, 

 are collected, for the most part, into three strong bands, which 

 being shorter, from end to end, than the other coats of the in- 

 testine, hold the canal in folds, bounding intermediate sacculi. 

 On the division of these bands, the intestine can be drawn out 

 to its full length, and it then assumes, of course, a uniformly 

 cylindrical form. In the rectum, the fasciculi of these longi- 

 tudinal bands spread out and mingle with the other longitudi- 

 nal fibres, forming with them a thicker layer of fibres than 

 exists on any other part of the intestinal canal. The circular 

 muscular fibres are spread over the whole surface of the bowel, 

 but are somewhat more marked in the intervals between the 

 sacculi. Towards the lower end of the rectum they become 

 more numerous, and at the anus they form a strong band called 

 the internal sphincter muscle. 



The mucous membrane of the large, like that of the small 

 intestine, is lined throughout by columnar epithelium, but, 

 unlike it, is quite smooth and destitute of villi, and is not pro- 

 jected in the form of valvulse conniveutes. Its general micro- 

 scopic structure resembles that of the small intestine. 



Glands of the Large Intestine. The glands with which the 

 large intestine is provided are of two kinds, the tubular and. 

 lenticular. 



The tubular glands, or glands of Lieberkiihn, resemble those 

 of the small intestine, but are somewhat larger and more 

 numerous. They are also more uniformly distributed. 



The lenticular glands are most numerous in the caecum and 

 vermiform appendix. They resemble in shape and structure, 

 almost exactly, the solitary glands of the small intestine, and, 

 like them, have no opening. Just over them, however, there 

 is commonly a small depression in the mucous membrane, 

 which has led to the erroneous belief that some of them open 

 on the surface. 



The functions discharged by the glands found in the large 

 intestine are not known with any certainty, but there is no 



