Till: INTESTINES. 413 



:u-.- mix'd with tin; convolutions of the small intestine. It afterwards 

 * into the pelvic cavity, to !; directly continued by the rectum. 



Morlr of attachment. Floating liku the small intestine, the small colon is 

 suspend. (! hy a serous layer, exactly similar to the in. -. nti TV proper, though 

 wider, ami named the coKc iin-n,-nti-rij. This mesentery is detached from the 

 siiblumliar region, not from around a central point, hut from a line extending 

 from the great mcseutcric artery to the bottom of the pelvic cavity. It is 

 narrower at its extremities than in its central portion. 



Interior. The internal surface of the floating colon shows vnlvular folds, 

 analogous to those of the caecum and large colon. It is in the intervals 

 between these that the faecal matters are moulded into balls. 



Structure. The serous membrane is without special interest, and the 

 >niix,-iiliir tunic is similar to that of the large colon. The mucous men-brane 

 is also the same. These membranes receive their blood by the small, and 

 a branch of the great, mesenteric artery. A venous trunk, passing between 

 the layers of peritoneum composing the mesentery, carries back the blood 

 to the vena portae. The lymphatics are nearly as fine and as numerous as 

 tin.se of the small intestine; they enter the game confluent, the reservoir of 

 1'ecqiit t. 



l'i NCTIONS OF THE COLON. In this intestine is accomplished the ab- 

 sorption of fluids, and of soluble alible matters. When the alimentary mass 

 arrives in the small colon, deprived of its assimilable principles and 

 charged with excretory substances thrown out on the surface of the intes- 

 timil tube, it loses its name and receives that of excrement or faces. These 

 excrements, compressed by the peristaltic contractions of the muscular tunic, 

 are divided into little rounded or oval masses, which find their way to the 

 rectum, where they accumulate, and whence, in due course, they are expelled. 



C. Rectum. (Fig. 204.) 



The rectum extends, in a straight line, from the entrance to the pelvic 

 i-avity to the posterior opening of the digestive canal, or anus. It is no- 

 thing more, properly speaking, than the extremity of the small colon, the 

 limit which separates them being somewhat arbitrary ; it differs from that 

 viscus, however, in having no ridges, and in its walls being thicker and more 

 dilatable, so that it can be distended into an elongated pouch, and form a 

 \oir or n ccptacle for the excrementitious matters until they are expelled. 



/,'- lull /ix. It responds, superiorly, to the roof formed by the os sacrum ; 

 inferiorly, to the. bladder, the del- -r nt canals. \vj-iculn- seminales, prostate 

 gland. ( 'owper's glands, or to the vagina and uterus; Literally, to the sides 



I'f the pelvis. 



If ode of attachment. There ought to bo considered as such: 1, The 



ri-.r extremity of the colic mesentery, representing the metorcctmn ; 

 1. An orbicular fold, constituted by the peritoneum in its circular reflection 

 around this viscera at the extremity of the pelvic cavity ; 3, The suspensory 

 ligaments of the penis, which, joining under the rctum. form a ring en- 

 circling the posterior extremity of the intestine \* Fig. 204 and the 

 d. M-ription of the penis; ; 4, A thick, triangular fasciculus, comprising two 

 Iat< ral parts, and compos, d of \\hite muscular fibres; this fasciculus, \\hich 

 illy a prolongation of the muscular tunic of the viscera, is detached from 

 the rectum above the anus, and is attached to the inferior aspect of the 

 1 bones, between the inferior sacro-coccygcal muscles, where its 

 outline can be wen beneath the skin when the tail is elevated. 



