It is wider, thicker, more vascular and of a deeper color than the ileum. The jejunum is about eight feet in length or two-fifths of the length of the small intestines. The arteries which supply the jejunum are the branches of the superior mesenteric artery. The veins are of the same name. The jejunum is fastened to the posterior wall of the abdomen by an extensive fold of the mesentery. =Ileum.=—The ileum is derived from a Greek word meaning to twist, and is so named on account of its numerous coils and convolutions. It is the third portion of the small intestines and is placed below the jejunum. It is much narrower and thinner than the jejunum, about twelve feet in length or three-fifths of the length of the small intestines. It is also attached to the posterior abdominal wall by means of the mesentery. The arteries which supply the ileum are the branches of the superior mesenteric artery. The veins are of the same name. _The villi_ are minute projections on the mucous membrane of the small intestines. They are largest and most numerous in the duodenum and jejunum, and become fewer and smaller in the ileum. It is in the villi of the intestines that we find the termination of the mesenteric arteries, the beginning of the mesenteric veins and the commencement of the lacteals. As the food passes down the intestines, having been previously prepared in the stomach and intestines for absorption, it comes in very close contact with the villi of the intestines and it is here that the nutrition from the food is absorbed through the villi wall into the lacteals, and hence carried to the receptaculum chylii. =The Large Intestines.=—The large intestine extends from the termination of the ileum to the anus. It is about five or more feet in length or about one fifth of the whole extent of the intestinal canal. It is largest at its commencement at the caecum, and gradually diminishes in size as far as the rectum, where there is a dilatation of considerable size just above the anus. The large intestine differs from the small intestine in its greater size, its more fixed position, its sacculated form. The large intestine in its course describes an arch, which surrounds the convolutions of the small intestines. It commences in the right inguinal region, in a dilated part of the caecum. It ascends through the right lumbar and the right hypochondriac regions to the under surface of the liver, it here takes a bend to the left, the hepatic flexure, and passes transversely across the abdomen on the confines of the epigastric and umbilical regions, to the left hypochondriac region; it then bends again, the splenic flexure, and descends through the left lumbar region to the left inguinal region, where it becomes convoluted and forms the sigmoid flexure; finally it enters the pelvic cavity and descends along the posterior wall to the anus.