THE ESSENTIAL PHENOMENA OF DIGESTION. 



37 



FIG. 21. 



The spleen is a thin, flat gland, of a dull-red color, situ- 

 ated in the left upper portion of the abdomen, and reach- 

 ing from the large 

 curve of the stomach 

 to the ribs. This 

 organ is usually con- 

 sidered as forming 

 part of the digestive 

 apparatus ; but up to 

 the present time its 

 functions remain un- 

 known. 



The liver weighs 

 sometimes as much 

 as four 'and a half 

 pounds, and is the 



the vis- 



THE UNDER SURFACE OF THE STOMACH AND 

 LIVER, WHICH ARE RAISED TO SHOW THE 

 DUODENUM AND PANCREAS. St, Stomach ; 



p, its pyloric end; I, liver; g, gall-blad- 

 der; d, duodenum, extending from the 

 pyloric end of the stomach to the front, 

 where the superior mesenteric artery, sm, 

 crosses the intestines; pa, pancreas; sp, 

 spleen ; a, abdominal aorta. 



largest of 

 cera. It occupies 

 the whole of the 

 right upper portion 



of the abdomen, and is divided into several lobes, sepa- 

 rated by depressions or furrows. It partly covers the 

 stomach, and is itself protected by the lower ribs. Its 

 internal structure is granular, being formed of little 

 glands, which secrete the bile, and of an elaborate vas- 

 cular net-work. For the bile there is a reservoir, called 

 the gall-bladder. The gall is a sort of liquid soap ; the 

 contents of the gall-bladder of the ox are used to wash 

 delicate fabrics. 



A duct leads from the gall-bladder, and another di- 

 rectly from the liver, and these unite to form the com- 

 mon gall-duct, which empties the bile into the small in- 

 testine, a little below the pyloric opening. When for any 



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