DIGESTION. 35 



the secretory activity of the pancreas is established, the granules disappear, 

 and the inner granular layer becomes reduced to a very narrow border 

 while the outer zone increases in size and occupies nearly the entire cell. 

 During the intervals of secretion, however, the granular layer reappears 

 and increases in size until the outer zone is reduced to a minimum. It 

 would seem that the granular matter is formed by the nutritive processes 

 occurring in the gland during rest, and is discharged during secretory 

 activity into the ducts and takes part in the formation of the pancreatic 

 secretion. 



The pancreatic juice is transparent, colorless, strongly alkaline and viscid, 

 and has a specific gravity of 1.040. It is one of the most important of the 

 digestive fluids, as it exerts a transforming influence upon all the classes of 

 alimentary principles, and has been shown to contain at least three distinct 

 ferments. It has the following composition : 



COMPOSITION OF PANCREATIC JUICE. 



Water, 900.76 



Albuminoid substances, 90.44 



Inorganic salts, 8.80 



100000 



The pancreatic juice is characterized by its action : ist. Upon starch. 

 When starch is subjected to the action of the juice, it is at once transformed 

 into glucose; the change takes place more rapidly than when saliva is 

 added. This action is caused by the presence of a special ferment, amyl- 

 opsin. 2d. Upon albumin. The albuminous bodies are changed by the 

 juice into, first, an alkali albumin, and then into peptone. The albumin 

 does not swell up, as is the case in gastric digestion, but is gradually cor- 

 roded and dissolved. This change is due to the presence of the ferment, 

 trypsin. Long-continued action of trypsin converts the peptones into two 

 crystalline bodies, leucine and tyrosin. 3d. Upon fats. The most striking 

 action of the pancreatic juice is the etnulsification of the fats or their sub- 

 division into minute particles of microscopic size. This change takes place 

 rapidly and depends upon the alkalinity of the fluid and the quantity of 

 albumin present, combined with the intestinal movements. The neutral 

 fats are also decomposed into their cor responding fatty acids and glycerine ; 

 the acids thus set free unite with the alkaline bases present in the intestine 

 and form soaps. This decomposition of the neutral fats is caused by the 

 ferment, steapsin. 4th. Upon cane sugar the juice also exerts a special 

 influence, converting it readily into glucose. 



