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HAND-BOOK OF PHYSIOLOGY. 



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

 appendix vermiformis. 



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

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

 serous coat need not be here particularly described. Connected with it 

 are the small processes of peritoneum, containing fat, called appendices 

 epiploiccB. The fibres of the muscular coat, like those of the small in- 

 testine, are arranged in two layers the outer longitudinal, the inner circu- 

 lar. 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, 



FIG. 193. Diagram of lacteal vessels in small intestine. A, lacteals in villi ; p, Peyer's glands; B 

 and D, superficial and deep network of lacteals in submucous tissue; L, Lieberkiihn's glands; E, small 

 branch of lacteal vessel on its way to mesenteric gland; H and o, muscular fibres of intestine; s, peri- 

 toneum. (Teichmann.) 



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

 shorter, from end to end, than the other coats of the intestine, 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 as- 

 sumes, of course, a uniformly cylindrical form. In the rectum, the fas- 

 ciculi 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 circular muscular fibres 

 are spread over the whole surface of the bowel, but are somewhat more 



