300 INTERNAL ANATOMY OF HOESE. 



domiiial cavity. Tlie cesophagus enters towards that end of the 

 gastric cavity known as the cardium, the other end being called 

 the pylorus. On opening the stomach we can distinguish a right 

 and a left half. The right half or pyloric half is lined by a red 

 mucous membrane, the left by a white mucous membrane, which 

 is partly continuous with the lining epithelium of the oesophagus, 

 which it receives. The right half only has, in its mucous 

 membrane, true digestive glands or gastric glands ; the left is in 

 reality part of the cesophagus much dilated. From the pyloric 

 end {Py), at which we may notice a constriction, arises the 

 commencement of the small intestine. The small intestine is 

 divided into three parts — the duodenum (B), which leaves the 

 pylorus, the Jejunum (Je), and the ileum (IT). The small intes- 

 tine is a long thin-walled tube much folded and convoluted, 

 and lies especially on the horse's left flank. It is 24 yards long 

 in the horse and about If inch in diameter. The jejunum 

 is situated chiefly in the left flank, and constitutes the main 

 part of the small intestine. The larrje intestine is much shorter 

 than the small, but of greater capacity. It is divided into two 

 portions — the CEecum and colon. The csecum, into which opens 

 the ileum, is marked off from the small intestine by the so-called 

 ileo-CcBcal valve. It is a large elongated sac ending bhndly at 

 one extremity [CAE). The csecum is largely developed in the 

 horse and all other herbivorous animals, containing as much 

 as 6 to 7 gallons of fluid. It is constricted and provided with 

 longitudinal bands of muscle, which on being cut cause the 

 constrictions to disappear. 



Close to where the ileum enters the cajcum is another opening, 

 from which springs the colon. The colon is divisible into two 

 regions — the large colon {Co^) and the floating colon (Co"). 

 This portion of the canal is also constricted at its commence- 

 ment, the constrictions being much more closely united. The 

 colon forms a loop surrounding the cascum, and towards the end 

 it gives rise to a straight thin-walled tube, the rectum (R), 

 which opens to the exterior by the anus. The colon is about 



