94 THE PANCREATIC JUICE. 



steapsin, which acts upon the fats; and amylopsin, which 

 converts starch into glucose. The ferments occur in the 

 gland in the form of inactive zymogens, but are changed 

 to the active form a few hours after death or by the action 

 of water or acids. The reaction of the juice is alkaline from 

 the presence of sodium carbonate. The extract made from 

 the gland by means of warm water may be acid in reaction 

 from the presence of sarco-lactic acid. 



The trypsin dissolves fibrin and other albuminous sub- 

 stances, but differs from pepsin in that it acts in a neutral 

 or weakly alkaline medium. With trypsin the fibrin does 

 not swell and become transparent before dissolving, as is 

 the case with pepsin, nor is acid albumin formed as the first 

 stage of digestion. The principal decomposition products 

 of fibrin by the action of trypsin are, first, a globulin 1 ; then 

 albumose and peptones; then leucin, tyrosin, asparatic 

 acid, and other amido compounds. A substance called 

 tryptophan (skatol-amido-acetic acid), which gives a red- 

 dish-violet precipitate with bromin-water or chlorin, is 

 produced. The antipeptones are not affected by the tryp- 

 sin. The hemipeptones are decomposed. 



The substances produced from albuminous substances 

 by the action of trypsin are: 



1. Globulin. 



I 



2. Albumose. 



I 



3. Peptones (called amphopeptones). 



4. Antipeptoue 5. Hemipeptone. 



(not further changed). 



Leucin, tyrosin, aspartic acid, tryptophan, etc. 



albuminous substances do not give a globulin when 

 acted upon by trypsin; e.g., serum-albumin. 



