COURSE OF THE INGESTA. 93 



of the stomach, and back along the small curvature. "While 

 the stomach thus keeps its contents in motion, its walls 

 rapidly absorb superfluous fluid, and at the same time 

 pour out the gastric juice. By united mechanical and 

 chemical action the food is gradually converted into pulp; 

 and the pyloric valve, which, at the commencement of diges- 

 tion, is kept quite closed, relaxes sufficiently to allow the 

 pulp to pass as rapidly as formed, thus allowing the whole 

 action of the stomach to be concentrated on the parts of its 

 contents which are not yet broken down. Gradually, how- 

 ever, in the later stages of digestion, the irritability of the 

 pyloric valve becomes exhausted, and at last even the most 

 indigestible solids are allowed to pass. 



61. The stomach is succeeded by the small intestine, a tube 

 about twenty feet long, and having a breadth of about an 

 inch and a half at the commencement, and an inch at its 

 termination. For about the first ten inches it is bound down 

 in a crescentic form to the back of the abdomen ; and this 

 part is termed the duodenum, and has the bile duct, and the 

 duct of a large gland, called the pancreas, opening into it close 

 together about its middle. The remainder of the small intes- 

 tine is not connected with the abdominal wall, except through 

 the medium of the mesentery a fold of the peritoneum or 

 lining membrane of the abdomen, containing within it vessels 

 and nerves. The upper third of this part of the intestine 

 gets the name of jejunum (empty), from usually containing 

 little but the pulp sent down from, the stomach, and here 

 termed chyme. But the more fluid portions of the chyme 

 get absorbed as it descends, and in the lower two-thirds of 

 the small intestine, the ileum, the contents are consequently 

 usually more solid. The ileuni opens into the large intestine 

 in the region of the right groin. 



62. The large intestine is about five or six feet long. It 

 begins in a short cul-de-sac, the ccecum (caput ccecum coli), 

 below the entrance of the ileum ; and into the extremity of 

 this there opens a small glandular structure, the vermiform 

 appendage, which represents the enormously large intestinum 

 caecum found in various animals, such as sheep and rabbits. 

 At first the large intestine passes directly upwards to a 

 point beneath the liver, and in this part of its course it is 



