DIGESTION. Ill 



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 1040. It is one of the most 

 important of the digestive fluids, as it exerts a transforming influence 

 upon all classes of alimentary principles, and has been shown to con- 

 tain at least three distinct ferments. It has the following com- 

 position : 



COMPOSITION OF PANCREATIC JUICE. 



Water 900.76 



Albuminoid substances ... 90.44 



Inorganic salts 8.80 



1,000.00 



The pancreatic juice is characterized by its action : 



1. Upon starch. When starch is subjected to the action of the juice, 

 it is at once transformed into maltose ; the change takes place more 

 rapidly than when saliva is added. This action is caused by the 

 presence of a special ferment, amylopsin. 



2. Upon albumin. The proteid bodies which escape digestion in 

 the stomach are converted into peptones by the action of the alkali 

 and ferment. The first effect of the alkali is to change the proteid 

 into an alkali-albumin, a fact which indicates that in the digestion 

 of albumin by pancreatic juice, the first stage is alkalinization. 

 This having been accomplished, the ferment trypsin transforms the 

 alkali-albumin into peptone. For the same reasons it is believed 

 that here also these bodies are preceded in their development by 

 albumoses, of which there are probably two forms. Long-contin- 

 ued action of the pancreatic juice, as previously stated, decomposes 

 the peptone into leucin, tyrosin, etc. 



3. Upon fats. The most striking action of the pancreatic juice is the 

 emulsification of the fats or their subdivision 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, 



