CH. XXVII.] THE INTESTINES 457 



the colon, continuous with the caecum, which forms the principal 

 part of the large intestine, and is divided into ascending, transverse, 

 and descending portions; and the rectum, which, after dilating at 

 its lower part, again contracts, and immediately afterwards opens 

 externally through the anus. Attached to the caecum is the small 

 appendix vermiformis. 



Like the small intestine, the large intestine is constructed of four 



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



coat has connected with it the r small processes of peritoneum containing 



I appendices epiploicce. The fibres of the muscular coat, like 



the small intestine, are arranged in two layers the outer 



nal, the inner circular. In the caecum and colon, the longi- 



bres, instead of being, as in the small intestine, thinly dis- 



all parts of the wall of the bowel, are collected, for the most 



three strong bands, which, being shorter, from end to end, than 



coats of the intestine, hold the canal in folds, bounding in- 



;e sacculi. On the division of these bands, the intestine can 



L out to its full length, and it then assumes a uniformly 



il form. In the rectum, the fasciculi of these longitudinal 



ead out and mingle with the other longitudinal fibres, form- 



thena a thicker layer of fibres than exists in any other part 



estinal canal. The circular muscular fibres are spread over 



3 bowel, but are somewhat more marked in the intervals 



the sacculi. Towards the lower end of the rectum they 



tiore numerous, and at the anus they form a strong ring 



3 internal sphincter muscle. 



IUGOUS membrane of the large, like that of the small intestine, 

 hroughout by columnar epithelium, but, unlike it, is quite 

 of villi, and is not projected in the form of valvulce con- 

 It is bounded below by the muscularis mucosce. The 

 cmct^ig^x^ent of ganglia and nerve-fibres in the large resembles that 

 in the small intestine. 



Glands. The glands with which the large intestine is provided } 

 are simple tubular glands, or glands of Lieberktihn ; they resemble j 

 those of the small intestine, but are somewhat larger and more ; 

 numerous, and contain a very great number of goblet cells ; nodules of 

 adenoid or lymphoid tissue are most numerous in the caecum and 

 vermiform appendix. They resemble in shape and structure the 

 solitary glands of the small intestine. Peyer's patches are not found 

 in the large intestine. 



Ileo-ccecal Valve. The ileo-caecal valve is situated at the place of 

 junction of the small with the large intestine, and guards against any 

 reflux of the contents of the latter into the ileum. It is composed of 

 two semilunar folds of mucous membrane. Each fold is formed by a 

 doubling inwards of the mucous membrane, and is strengthened on 



