98 PRINCIPLES OF PHYSIOLOGY 



appear to be indispensable, as many animals 

 have no such reservoir. 



Along with the bile from the liver, the 

 pancreatic fluid enters, often by a duct formed 

 by the confluence of the ducts of the two 

 glands This fluid is secreted only during 

 the digestive process, and the secretion appears 

 to be stimulated and modified in character 

 by a special enzyme in the duodenum called 

 secretin, a remarkable example of a ferment 

 body acting so as to excite the activity of 

 another enzyme-forming gland. Another 

 enzyme, known as entero-kinase, formed in 

 the duodenum, appears to facilitate the 

 action of one of the pancreatic ferments, 

 trypsin The pancreatic fluid is assumed 

 to contain three ferments : (1) one acting 

 on proteins and peptones, called trypsin, 

 splitting those up into simpler bodies, 

 mainly such as leucin and tyrosin (crystal- 

 lizable bodies) ; (2) another, amylopsin, acting 

 on the starch, cooked or raw, which has escaped 

 the saliva, changing it into grape sugar ; and 

 (8) one that acts on fats, lipase, splitting them 

 up into glycerine and a fatty acid, while the 



