232 INTESTINAL DIGESTION. 



coats i. e., peritoneal, muscular, cellular, and internal 

 mucous. 



The peritoneal tunic forms an entire covering to the large 

 intestine, with the exception of the superior surface of the 

 transverse colon which is in contact with the pancreas 

 and the terminating portion of the rectum. The bands by 

 which it unites the intestine to other parts have been already 

 described. In addition to the peritoneum forming an entire 

 covering, at the attached margin of the flexures of the colon, 

 it constitutes folds loaded with fat, varying in width indifferent 

 parts, and clustered so as to have deserved the name of ap- 

 pendices epiploica3. 



The muscular coat of the large intestine is differently de- 

 veloped in various parts. Its fibres are of the plain variety, 

 and arranged in two orders. The outer longitudinal set is 

 scanty in some parts, but in others forms the longitudinal 

 bands above alluded to. These are shorter than the actual 

 length of the gut itself, so as effectually to pucker it. The 

 number of longitudinal bands varies from one to four in the 

 various parts of the gut, and the shape and breadth of the lat- 

 ter is not everywhere the same. The longitudinal fibres are 

 abundant in the rectum, but they only form bands in the an- 

 terior two-thirds, as posteriorly to this they uniformly surround 

 the intestine. The inner layer of fibres encircles the whole of 

 the latter, being thickest towards the apex of the caecum, as 

 well as in the single colon and rectum : at the end of the 

 latter .ne internal sphincter ani is formed by an accumula- 

 tion of the circular fibres. The circular fibres of the colon 

 are engaged in forming the ileo-colic valve, hereafter to be 

 described. 



The cellular coat of the large intestine resembles that of 

 the small, only it is not so abundant, except at the terminathg 

 portion of the rectum, where it is much more developed. 



