348 HUMAN PHYSIOLOGY 



4. Trypsin acts in O'Ol percent, ammonia while amylopsin 

 does not. 



5. The proportion of the zymins varies with the character 

 of the diet. 



This is well shown by experiments carried out in Paw low's 

 laboratory upon dogs with pancreatic fistuke. The effects of 

 diets of milk, bread, and flesh were compared, in each case 

 the amount of the food given containing the same amount 

 of nitrogen (proteid). The total quantity of ferment unit 

 is got by multiplying the quantity of the juice in ccrn. by 

 the strength of the juice. The following table indicates the 

 results obtained : 



Quantity of Enzyme. 

 Diet. 



Proteolytic. 



BOO 



Bread, 250 grin. . . ! 1978 1601 



Milk, 600 cc 1085 432 



Flesh, 100 grm. . . | 1502 648 8000 



Amylolytic. Fat Splitting. 



Bread contains a proteid difficult of digestion, plenty of starch, 

 and little fat. Milk contains an easily digested proteid, and 

 plenty of fat, but no starch; while flesh contains a com- 

 paratively easily digested proteid, no starch, and little fat. 

 The first food causes a copious production of trypsin and 

 amylopsin, and little pialyn. The second causes the produc- 

 tion of less trypsin, little amylopsin, but most pialyn. The 

 last causes a moderate production of trypsin, little amy- 

 lopsin, and a comparatively large amount of pialyn. 



As to the mode of production of these enzymes, it is 

 known that trypsin is not formed as such in the cells, but 

 that a forerunner of trypsin trypsinogen is produced, and 

 that this changes into trypsin after it is secreted. The in- 

 testinal secretion contains something which has been termed 

 enterokinase, which has the power of bringing about this 

 change, and in all probability the cells lining the ducts of 

 the pancreas also produce this or a similar substance. 



It is doubtful whether the pancreatic secretion contains 



