362 VETERINARY PHYSIOLOGY 



On nucleo-proteins trypsin acts by digesting the protein and 

 dissolving the nucleic acid so that it can be absorbed. 



On collagen and elastin trypsin has little action ; but on 

 gelatin it acts as upon proteins. 



2nd. An Amyloid/tic Enzyme Amylopsin or Diastase. This 

 acts in the same way as ptyalin, but more powerfully, convert- 

 ing a certain part of the maltose into dextrose. It acts best 

 in a faintly acid medium. 



3rd. A Fat Splitting Enzyme Lipase. This is the most 

 easily destroyed and the most difficult to separate of the 

 zymins. It breaks the fats into their component glycerin and 

 fatty acids. The fatty acids link with the alkalies which are 

 present to form soaps, and in this form, or dissolved as free 

 fatty acids in the bile, they are absorbed. But the formation 

 of soaps also assists the digestion of fats by reducing them 

 to a state of finely divided particles, an emulsion, upon which 

 the lipase can act more freely. This process of emulsification 

 is assisted by the presence of protein in the pancreatic juice 

 and also by the presence of bile. 



That these enzymes are independent of one another is shown 

 by many facts. 



1. Diastase does not appear till about a month after 

 birth. 



2. Diastase is taken up by dry glycerin while trypsin is 

 not. 



3. Trypsin may be precipitated and separated by shaking 

 with collodion. 



4. Trypsin acts in O'Ol per cent, ammonia while diastase 

 does not. 



5. The proportion of the zymins varies with the character 

 of the diet. 



This is well shown by experiments carried out in Pavlo\ 

 laboratory upon dogs with pancreatic fistulse. 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 (protein). The total quantity of ferment unit is 

 got by multiplying the quantity of the juice in c.cm. by the 

 strength of the juice, determined by ascertaining how much 

 of the substance is digested by unit of the secretion in unit 



