THE HORSE. 



107 



toneum coming off on to it from the cae- 

 cum, in the right iliac fossa, and continues 

 from the outer flexure on to the inner, so as 

 to keep the two in perfect apposition. Thus, 

 if the abdominal parietes are cut through, 

 the whole of the double colon may hang 

 out, with the exception of the transverse 

 portion. The latter is attached to the right 

 kidney, as well as concave surface of the 

 liver, by folds of peritoneum ; to the spine 

 by the transverse meso-colon ; and still 

 more to the left, it is loosely attached by 

 the gastrocolic omentum to the stomach 

 and spleen; besides which it has a peri- 

 toneal attachment to the left kidney. Then 

 the single colon commencing, it is loosely 

 affixed to the spine by an extensive peri- 

 toneal fold, the meso-colon, similar to the 

 mesentery, but smaller and to its left : this 

 fold is continuous posteriorly with the meso- 

 rectum. 



The relations of the transverse colon are 

 important, no less than interesting, inas- 

 much as it is in close connection with the 

 most important abdominal viscera. On the 

 right, its upper surface is contiguous to the 

 right kidney, as well as to the right and 

 Spigelian lobes of the liver. In the middle, 

 its superior surface is connected princi- 

 pally with the pancreas; and to the left, 

 but still superiorly, it approaches the left 

 kidney and spleen. Anteriorly, the stomach 

 also touches it, especially during repletion. 



The shape of the colon is very variable 

 in different parts of its course. Thus, the 

 first portion of the double colon, from the 

 right iliac fossa till it forms the signoid 

 flexure, is capacious and sacculated; the 

 latter being due to the four bands con- 

 tinuous on to it from the caecum. At the 

 signoid flexure the bands are completely 

 lost, so that the gut is smooth ; but, as we 

 extend up towards the diaphragm, the an- 

 terior band begins, and then the posterior 

 one becomes apparent; so that the trans- 

 verse and single portions of the colon 

 are puckered by two longitudinal bands. 



The Rectum, so called from its compar- 

 ative straight course through the pelvic 

 cavity, arises from the single colon, a little 



anteriorly to the posterior mesenteric artery, 

 and ends at the anus, where its mucus 

 membrane is continuous with the common 

 tegumentary covering. It is attached in its 

 anterior two-thirds by a meso-rectum ; the 

 posterior third is an exception to any other 

 part of the intestinal track, in so far as it 

 is connected to adjacent parts by special 

 faschisB, and at its termination by certain 

 muscles hereafter to be dwelt upon. 



The size of the rectum is much the same 

 as the single colon. It is puckered in its 

 anterior part by two longitudinal bands ; 

 and the sacculi, resulting therefrom, deter- 

 mine the shape of the faecal matters. 



The rectum is superiorly related to the 

 spine, whilst inferiorly it comes in contact 

 with the bladder, bulbous portions of the 

 vasa deferentia, vesiculse seminales, and 

 prostate. 



The structure of the large intestine does 

 not vary essentially from that of the small, 

 as it possesses the four coats, i. e. peritoneal, 

 muscular, cellular, and internal mucus. 



The peritoneal tunic forms an entire cov- 

 ering to the large intestine, with the excep- 

 tion of the superior sm*face of the trans- 

 verse colon — which is in contact with the 

 pancreas — and the terminating portion of 

 the rectum. The bands by w^hich it unites 

 the intestine to other parts have been already 

 described. In addition to the peritoneum 

 forming an entire covering to the gut, at 

 the attached margin of the flexures of the 

 colon it constitutes folds loaded with fat, 

 varying in width in different parts, and clus- 

 tered so as to have deserved the name of 

 appendices epiploicse. 



The muscular coat of the large intestine 

 is differently developed in various parts. 

 Its fibres are of the plain variety, and ar- 

 ranged in two orders. The outer longitud- 

 inal set is scanty in some parts, but in others 

 forms the longitudinal bands above aUuded 

 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 various parts of 

 the gut, and the shape and breadth of the 

 latter is not everywhere the same. The 



