=The Large Intestine.=--The large intestine differs from the small in size and in fixity of position, lying curved in horseshoe shape above and around the small intestine. It is five or six feet long, large in caliber, and is thrown into crosswise folds. It has the same four _coats_ as the small intestine, but the mucous coat is pale and smooth, without villi. Its _glands_ are the crypts of Lieberkühn and the solitary glands. The _arteries_ are branches of the superior and inferior mesenteric and the _nerves_ come from sympathetic plexuses. The blind sac lying in the right iliac fossa, with which the large intestine begins, is called the _cecum_, and into this the ileum opens, the ileo-cecal valve preventing regurgitation. Just below the ileo-cecal opening is the _vermiform appendix_, a narrow, worm-like tube with a blind end, varying in length from one to nine inches, but generally about four and one-half inches long, which, so far as is known, is functionless as well as dangerous. People have been born without an appendix and it has in rare instances grown again after operation. Its base is located in the living by _McBurney’s point_, a point two inches from the anterior superior spine of the ilium on a line drawn from the spine to the umbilicus. From the cecum the intestine ascends in what is known as the _ascending colon_ along the abdominal wall at the right to the under surface of the liver, where it turns in the _hepatic flexure_ abruptly across the body to the left, passing below the liver, stomach, and spleen in the _transverse colon_. In the _splenic flexure_ it turns down the left abdominal wall, the _descending colon_ passing to the crest of the ilium, where there is another curve, the _sigmoid flexure_, leading to the _rectum_, which passes for six or eight inches down along the vertebræ, a little to the left, to the _anus_, the external opening. This opening is guarded by two _sphincter muscles_, about an inch apart, the internal and external sphincters. The coils of the small intestine lie below the transverse colon, covered mostly by the omentum. The splenic flexure is behind the stomach and below the spleen and is slightly higher than the hepatic flexure. The sigmoid flexure can be felt in the left inguinal region in thin people. The fact that the _rectum_ is somewhat to the left is of importance in childbirth because if the rectum is packed, it may turn the child’s head in the wrong direction.