SPLANCHNOLOGY. 195 



duodenum, the process of digestion is completed ; the chyme is mixed with 

 the biliary and pancreatic juices, and a separation takes place between the 

 chyle and the excrementitious matter. 



3. The Jejunum and Ileum Intestines are partly concealed by the 

 omentum. There is no exact division between these two portions, the upper 

 two üfths being named jejunum, and placed higher in the abdomen than 

 the remaining ileum. From the duodenum the jejunum first passes forwards 

 and to the left side ; it then descends into the middle of the abdomen, is 

 folded upon itself over and over again, extending into various regions ; 

 finally, the terminating portion of the ileum rises out of the pelvis from left 

 to right, and joins the coecum at an acute angle convex upwards. This 

 portion of the intestinal tract is well supported b}^ the mesentery, so that 

 while possessing sufficient freedom of motion, and the power of accommo- 

 dating itself to the various displacements produced by muscular action, it is 

 securely tied in its place. 



The large intestine, from four to five feet long, is divided into coecum, 

 colon, and rectum. It differs from the small, not only in size but in being 

 cellular or sacculated when distended ; small processes too, appendices 

 epiploicce^ are attached to it. Three strong longitudinal muscular bands may 

 be observed, puckering it and causing the cellular appearance. 



The coecum^ or capxd coli^ is a cul de sac in the right iliac fossa, which it 

 nearly fills. It joins the colon at an obtuse angle, although there is no 

 exact limit between them. On its external surface there are three irregular 

 protuberances, one anteriorly and the other posteriorly. The appendix ver-- 

 mifonnis proceeds from the left side of the lower and posterior part ; this is 

 a small tortuous cul de sac about the size of a goose quill, and may be con- 

 sidered as representing the more highly developed coecum of other animals. 

 The ileum joins the left or inner side of the coecum at an acute angle, its 

 mucous coat protruding into the cavity of the coecum to form two valves. 

 The inferior or ilio-coecal valve is the larger ; it secures the ileum against 

 regurgitation from the coecum; the superior or ilio-colic valve is smaller, and 

 prevents regurgitation from the colon. These two valves are united at their 

 commissures or extremities, and from each commissure a fold is continued 

 round on the inner side of the coecum ; these folds are the froena or retinacula 

 of the valves. 



4. The Colon extends from the coecum to the rectum ; it is divided into 

 four portions. The right or ascending colon extends from the coecum to the 

 inferior surface of the right lobe of the liver. The transverse arch of the 

 colon turns off at a right angle from the last, and extends tortuously from 

 the gall bladder, transversely as far as the spleen in the left hypochondrium. 

 The left or descending colon extends from the spleen to the iliac region behind 

 the small intestines, and the sigmoid ßexxire or the fourth division completes 

 the colon to the rectum. 



0. The Rectum, or straight intestine, extends from the sigmoid flexure 

 of the colon to the anus. It is more cylindrical and less sacculated than 

 the colon ; it is usually found much dilated about an inch above the anus. 



The mucous coat of the small intestines, although continuous with that 



i.Ol 



