472 DIGESTION. 



observed the reverse in man, that is, after carbohydrate feeding the 

 smallest amount of juice was secreted, and with a mixed diet about the 

 same amount as after the partaking of protein or fat. Objections have 

 also been raised in many quarters against PAWLOW'S teachings as to an 

 accommodation of the quantity of enzyme to the kind of food, and some 

 of the observations on which these teachings are based have been some- 

 what differently explained in the light of recent investigations on the 

 conditions necessary for the activation of the trypsinogen. 



PAWLOW and his pupils, especially SCHEPOWALNIKOFF, have shown 

 that the above-mentioned (page 468) enterokinase activates the trypsino- 

 gen into trypsin. These observations were later confirmed by others, 

 by DELEZENNE and FROUIN, POPIELSKI, CAMUS and GLEY, BAYLISS and 

 STARLING, UNZ, and have been further studied. The pure juice con- 

 tains, at least as a rule, only trypsinogen, and no trypsin. By mixing with 

 the intestinal juice, or by contact with the intestinal mucosa, the tryp- 

 sinogen is converted into trypsin by the klnase. Enterokinase, which 

 itself has no action upon proteins, and therefore is not a proteolytic 

 enzyme, is not well known. It is made inactive by heating and is therefore 

 considered by many (including PAWLOW) as an enzyme. Others, an the 

 contrary, like HAMBURGER and HEKMA, DASTRE and STASSANO, deny the 

 enzyme nature of enterokinase because they find that a certain quantity 

 of intestinal juice will activate only a certain quantity of trypsin. 

 Enterokinase has been found in man and all mammals investigated. 

 According to most investigators it is formed in the glands or the cells 

 of the intestinal mucosa, while according to DELEZENNE it comes from 

 PEYER'S patches and from the lymph-glands and leucocytes, hence 

 impure fibrin containing leucocytes acts as a kinase. These deductions 

 of DELEZENNE are disputed by BAYLISS and STARLING, HEKMA and others. 



From the experience with enterokinase, the report as to the accom- 

 modation of the enzyme content of the juice to the kind of food has also 

 been explained by the fact that after different foods the proteolytic 

 power of the juice becomes unequally activated (LTNTWAREW and others). 

 For instance, a diet of bread and milk causes the secretion of a large 

 quantity of juice which is rich in trypsinogen but contains almost no 

 trypsin, while after a rich meat diet the secretion becomes scant and the 

 juice contains only trypsin but no trypsinogen. The theory based upon 

 the investigations of DELEZENNE, FROUIN, POPIELSKI, BAYLISS and STAR- 

 LING, PRYM, and others, 1 that the pure juice collected under the influence 

 of the food contained only trypsinogen but no trypsin, opposes this 



1 In regard to the literature on enterokinase, secretin, and secretion of pancreatic 

 juice, see O. Cohnheim, Biochem. Centralbl., 1, 169, and S. Rosenberg, ibid., 2, 708; 

 Prym, Pfliiger's Arch., 104 and 107. 



