Results are plotted into tlie annexed curve (I). As can be seen 

 there is no point of optimal action but a broad optimal zone 

 extending from a Pn of about 3,5 till about 5,5. 



Neither the concentration of the amjlase, nor the composition of 

 the nutritive liquid appeared to have influence. The same results 

 were obtained with amj'lase extracted from the mycelium. 



These results largely confirm the theory of Michaïélis who con- 

 siders the enzymes as ampholytes (2 and 3). The form of the curve 

 indeed is nearly identical to the dissociation rest curve of an amphotere 

 electrolyte. According to his formulas 



1 



1 + 



Ka 



and ^6 



1 



1 + 



Kb 



(H) - ' (OH) 



in which ^ = 1 — y = dissociation rest 



7 = rate of dissociation 



Ka = dissociation constant of the acid 



Ki, =: dissociation constant of the base 



the points on the ordinate := half of the maximum height of the 

 curve indicate the logarithms of the dissociation constants of acid 

 and base on the abscissa. These are to be found at about 2,26 and 

 6,2. So the dissociation constant of the acid would be =:6.3 X 10"-^, 

 that of the base = 2.884 X IO-12. 



We may consider in the same way curve 11 which represents 



