[Illustration: A view of the Organs of Digestion, opened in nearly their whole length; a portion of the œsophagus has been removed on account of want of space in the figure; the arrows indicate the course of substances along the canal: 1, the upper lip, turned off the mouth; 2, its frænum; 3, the lower lip, turned down; 4, its frænum; 5, 5, inside of the cheeks, covered by the lining membrane of the mouth; 6, points to the opening of the duct of Steno; 7, roof of the mouth; 8, lateral half-arches; 9, points to the tonsil; 10, velum pendulum palati; 11, surface of the tongue; 12, papillæ near its point; 13, a portion of the trachea; 14, the œsophagus; 15, its internal surface; 16, inside of the stomach; 17, its greater extremity or great cul-de-sac; 18, its lesser extremity or smaller cul-de-sac; 19, its lesser curvature; 20, its greater curvature; 21, the cardiac orifice; 22, the pyloric orifice; 23, upper portion of duodenum; 24, 25, the remainder of the duodenum; 26, its valvulæ conniventes; 27, the gall-bladder; 28, the cystic duct; 29, division of hepatic ducts in the liver; 30, hepatic duct; 31, ductus communis choledochus; 32, its opening into the duodenum; 33, ductus Wirsungii, or pancreatic duct; 34, its opening into the duodenum; 35, upper part of jejunum; 36, the ileum; 37, some of the valvulæ conniventes; 38, lower extremity of the ileum; 39, ileo-colic valve; 40, 41, cœcum, or caput coli; 42, appendicula vermiformis; 43, 44, ascending colon; 45, transverse colon; 46, 47, descending colon; 48, sigmoid flexure of the colon; 49, upper portion of the rectum; 50, its lower extremity; 51, portion of the levator-ani muscle; 52, the anus.]