36 ORGANS OF DIGESTION. 



the descending portions of the colon, however, where the latter 

 comes in contact with the parietes of the abdomen, the perito- 

 neum does not invest it entirely; but the transverse portion or 

 the arch, as it is called, and the sigmoid flexure, are completely 

 surrounded. 



The surface of this intestine is studded with small projections 

 of various lengths, called Appendices Epiploicse, which are small 

 duplicatures of peritoneum containing fat. 



The Muscular Coat is thin, and like that of the small intestine, 

 consists of two orders of fibres, the longitudinal, and the trans- 

 verse or circular. 



The longitudinal fibres have the peculiarity of being collected 

 into three equidistant, flattened fasciculi or bands, of about half 

 an inch in breadth, which begin by a common point at the ex- 

 tremity of the coecum, and extend to the upper end of the rec- 

 tum. One of them is along the line of junction with the meso- 

 colon, another anterior, and the third inferior. These fibres, 

 being shorter than the other coats of the gut, have the effect of 

 puckering them into the internal cellular condition alluded to ; 

 for, when they are cut through, the intestine is much elongated, 

 and its cells disappear. It occasionally happens that the longi- 

 tudinal fibres, instead of being confined to the bands alluded to, 

 exist in considerable quantity over the intermediate spaces ; in 

 this case the cellular arrangement is restricted, and in some in- 

 stances entirely dispensed with; of the latter, an example is in 

 the Anatomical Museum. 



The circular muscular fibres form a thin semi-transparent la- 

 mina beneath the last, and do not present any peculiarity of in- 

 terest, they are somewhat thicker than in the small intestine. 



The Cellular Coat is a thin lamina of dense cellular substance, 

 serving to connect the muscular with the mucous coat, and to 

 conduct the blood vessels and nerves to their terminations on 

 the latter. 



The Mucous Coat lines smoothly the internal face of the cel- 

 lular, and has no doubling or folds, exclusively in it, like the 

 valvulae conniventes of the small intestine.* The transverse 



* This may be considered as the general rule: if it be examined, however, in 

 its whole length, here and there narrow ones may be found. 



