44 PROTEOLYTIC PANCREATIC FERMENT 



it is interesting to note the return of its efficiency as soon 

 as the normal salts of pancreatic fluid are added. 23 Only 

 the briefest comment can here be made upon the extensive 

 literature dealing with the influence of variations of alkalin- 

 ity, temperature, neutral salts, poisons of various kinds, 

 6 ' antif erments " and adsorbing media upon the activity of 

 trypsin; the author must refer for fuller details of these 

 subjects to Carl Oppenheimer 's valuable work on ferments. 24 



Conversion of Trypsin into Zymoid. The observations 

 of Bayliss are presumably of general interest as they may 

 perhaps bring us a step nearer to comprehension of the 

 mystery of ferment activities. By determination of con- 

 ductivity Bayliss discovered that trypsin inactivated by 

 standing does not lose its power of fixation of protein. 

 He compares the inactivation of trypsin to Ehrlich's 

 conception of the change of a toxine into a toxoid. In 

 the transformation of trypsin into a " zymoid" he sup- 

 poses it loses its ergophore group, still retaining, however, 

 its haptophore group, which serves to fix it to a protein 

 molecule. There has been no lack of experiments with other 

 ferments to apply to the enzyme problem the conceptions 

 which have come in spite of all opposition to dominate our 

 theories as to immunity. We may think as we will of these 

 modes of thought ; the heuristic value of these and of similar 

 schematic ideas cannot be controverted. Their justification 

 can be maintained, however, only until something better can 

 be substituted. 25 



Action of Trypsin Upon Polypeptids. Undoubted prog- 

 ress has been accomplished by the systematic researches of 

 Emil Fischer, Abderhalden and Bergell in determining the 



"A. Frouin and A. Compton, Compt. rend., 153, 1032, 1911. 



* C. Oppenheimer, Fermente, 3d ed., pp. 185-202, 1909; cf. also S. G. Hedin, 

 Biochem. Journ., 1, 474,"484, 1906; 2, 81, 1907; L. Michaelis and H. Davidsohn, 

 Biochem. Journ., 36, 280, 1910. 



" W. M. Bayliss, Arch. Sciences biol., St. Petersburg, 11, supplement 261,. 

 cited by 0. Cohnheim, Nagel's Handb. d. Physiol., 2, 582, 1907. 



