FOOD AND DIGESTION. 377 



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 immedi- 

 ately afterward opens externally through the anus. Attached to the 

 caecum is the small appendix vermiformis. 



Structure. Like the small intestine, the large intestine is con- 

 structed of four principal coats, viz., the serous, muscular, sub-mucous 

 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 longitudinal, 

 the inner circular. In the caecum and colon, the longitudinal fibres, be- 

 sides 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, 



Fi~. 2G3.-A. Villus of sheep. B. Villi of man. (Slightly altered from Teichmann.) 



and it then assumes, of course, an uniformly cylindrical form. In the 

 rectum, the fasciculi of these longitudinal bands spread out and mingle 

 with the other longitudinal fibres, forming with them a thicker layer of 

 fibres than exists on any other part of the intestinal canal. The circu- 

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



