PHYSIOLOGY OF THE DIGESTIVE GLANDS 443 



tween ligatures, and then denervating the central pouch by carefully 

 cutting all the nerves without wounding the blood vessels. On returning 

 the pouches to the abdomen and leaving them several hours, it has been 

 found that the middle pouch becomes distended with secretion, whereas 

 the two end pouches remain empty (Fig. 152). If the pouches are left for 

 several days in the abdomen, however, the secretion from the denervated 

 portion disappears again. The explanation of the result is possibly that 

 the nerves under ordinary conditions convey impulses to the intestinal 

 glands, which tonically inhibit their activity. 



The existence of hormone control is evidenced by the fact that no 

 enteroldnase is present in the intestinal juice unless pancreatic juice is 

 placed in contact with the mucous membrane. Injection of pancreatic 

 juice into the blood, however, does not cause any secretion of intestinal 

 juice ; whereas the injection of secretin has such an effect. 



