3l8 THE EVOLUTION OF MAN. 



especially takes place. The stomacli of an adult man 

 (Fig. 275, Plate V. Fig. 16, m,g) is an oblong sac, placed 

 somewhat obliquely, the left side of which widens into 

 a blind-sac, the base of the stomach or fundus (b), while the 

 right side narrows, and passes at the right end, called 

 the pylorus (e), into the small intestine. Between these two 

 parts of the intestine is a valve, the pyloric valve (d), which 

 only opens when the food-pulp (chyme)' passes from the 

 stomach into the small intestine. The stomach itself is the 

 most important digestive organ, and serves especially to 

 dissolve the food. The muscular wall of the stomach is 

 comparatively thick, and, on the outside, has strong muscle- 

 layers, which effect the digestive movements of the 

 stomach ; — on the inside, it has a great number of small 

 glands, the gastric glands, which secrete the gastric juice. 



Next to the stomach follows the longest part of the 

 whole intestinal canal, the central, or small intestine 

 (chylog aster). Its principal function is to effect the absorp- 

 tion of the fluid mass of digested food, or the food-pulp 

 (chyme), and it is again divided into several sections, the 

 first of which, the one immediately following the stomach, 

 is called the gall-intestine, or "twelve-finger intestine" 

 {duodenum, Fig. 275, fg h). The gall-intestine forms a short 

 loop curved like a horse-shoe. The largest glands of the 

 intestinal canal open into it : the liver, the most important 

 digestive gland, which furnishes the bile, or gall, and a very 

 large salivary gland, the ventral salivary gland, or pancreas, 

 which secretes the digestive saliva. Both of these glands 

 pour the juices they secrete, the bile and pancreatic juice, 

 into the duodenum (i) near each other. In adults the liver 

 is a very large gland, well supplied with blood, lying on the 



