HORMONES 41 



the sweetbread, or, better, the stomach sweet- 

 bread, to distinguish it from the thyroid gland 

 which is called by butchers, from its location, 

 throat sweetbread. 



The pancreas in man produces a copious 

 secretion, as much as from five hundred to 

 eight hundred cubic centimeters per day. 

 This secretion is poured into the duodenum 

 through the pancreatic duct and is one of the 

 most important digestive juices. It aids in the 

 solution of almost all the constituents of our 

 food. The pancreatic juice is apparently pro- 

 duced in small amounts continuously, but the 

 major production and discharge is associated 

 with the taking of food. The increase of pro- 

 duction begins soon after food has entered 

 the stomach and develops to a maximum in 

 from two to four hours; it then gradually 

 falls off with the completion of digestion. 



Almost two decades ago it was shown that 

 when acid solutions were applied to the mu- 

 cous surface of the duodenum, the flow of pan- 

 creatic juice was excited, and as the natural 

 contents of the stomach are acid, it was be- 

 lieved that, after they had passed into the 

 duodenum, their acidity was the normal stim- 

 ulus for the reflex mechanism controlling the 



