40 BIOLOGY AND SOCIAL PROBLEMS 



ality, the doctrine of the humors was relegated 

 to the rubbish heap of worn-out ideas and dis- 

 appeared from view. Within late years, how- 

 ever, this doctrine, in principle at least, has 

 been revived, and recent investigations prom- 

 ise to give it renewed life, though not of such 

 general scope as it once enjoyed. The fluids 

 circulating in the bodies of animals, including 

 man, are undoubtedly highly important and 

 significant means of controlling the responses 

 of these forms and of determining their states, 

 mental and otherwise. Among the recent dis- 

 coveries which have been important in open- 

 ing up this point of view are those concerning 

 the action of the pancreas, a gland which was 

 supposed to be brought into activity through 

 the ordinary channels of nervous reflex. 



The pancreas is a long, narrow gland ex- 

 tending from the neighborhood of the spleen 

 on the left side of the abdomen to the right 

 side of that cavity where its duct opens into 

 that portion of the small intestine known as 

 the duodenum. This opening is three or four 

 inches from the outlet of the stomach, there- 

 fore near the beginning of the duodenum, and 

 very close to the opening of the bile duct from 

 the liver. The pancreas is popularly known as 



