DIGESTIVE APPARATUS. 



493 



portion of it which is fit to be assimilated or converted into organized texture, 

 from that which cannot serve this purpose, and which is at once rejected ; 

 and the alteration (when required) of the chemical constitution of the former, 



[Fig. 199. 



A view of the Org*ns of Digestion, opened in nearly their whole length; a portion of the oesophagus 

 has been removed on account of want of space in the figure ; the arrows indicate the course of sub- 

 stances along the canal ; 1. the upper lip, turned off the mouth; 2, its frrenum ; 3, the lower lip, turned 

 down ; 4, its franum ; 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 tonsils; 

 10, velum pendulum palati ; 11. surface of the tongue ; 12, papillae near its point ; 13, a portion of the 

 irachea ; 14, the oesophagus ; 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; 2-2, the pyloric orifice; 23, upper portion of duodenum; 24, 25, the 

 remainder of the duodenum ; 26, its valvulse 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 open- 

 ing 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 valvuloe conniventes; 38, lower extremity 

 of the ileum; 39, ileo-colic valve; 40,41, ccecum, or caput coli ; 42, appendicula vermiformis; 43.44, 

 ascending colon ; 45, transverse colon ; 46, 47, descending colon ; 43, 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.] 



42 



