BIBLIOGRAPHY 91 



tion of the undissociated substance and c 2 that of either of the 

 two dissociated cleavage products. Now if we suppose that pepsin 

 is a substance which is very feebly dissociated, and that it is only 

 the dissociated portion which is active as an enzyme, then there 

 follows an easy explanation of the Schiitz law. For, the substance 

 being but feebly dissociated, c 2 is very small compared to c l3 and 

 if C be the total concentration in enzyme we can write instead 

 of the above equation C = k c\. But the activity is proportional 

 to the dissociated portion c 2 and hence to ^/C, which is Schutz's 

 law. 



However, it is a quite unproven hypothesis that an enzyme 

 dissociates into an active and an inactive part, and considering 

 the nature of enzymes as colloids, an exceedingly improbable one. 



Medwedew found for the oxydase of liver tissue the law that 

 the intensity of action of the enzyme is directly proportional to 

 the square of the concentration and not the square root as in 

 Schutz's law. This might receive an " explanation " by making 

 the hypothesis that the ferment is practically all dissociated, 

 and that it is the smaller undissociated portion only which 

 retains activity ; but the writer prefers to believe that it is an 

 approximate empirical expression for a small portion only of 

 the curve expressing the relationship between concentration and 

 activity. 



The conclusion may therefore be drawn that in the case of each 

 enzyme, there is in dilute solutions a range of concentration throughout 

 which the activity increases approximately directly as the concentra- 

 tion, and as the concentration increases a farther period in which 

 there is also an increase but at a less rapid rate than the concentra- 

 tion, and that finally a maximum effect is obtained beyond ivhich 

 increasing the concentration has no action in increasing the activity. 



BIBLIOGRAPHY 



H. E. Armstrong, Chem. Soc. Trans., vol. Ivii. (1890), p. 528 ; Proc. Roy. 

 Soc., vol. Ixxiii. (1904), p. 500. 



Bayliss, Arch, des Sciences biologiques, vol. xi., Suppt., p. 261, St. Peters- 

 burg (1904). 



E. F. Armstrong, Proc. Roy. Soc., vol. Ixxiii. (1904), p. 500 et seq. 



E. F. Armstrong and Caldwell, Proc. Roy. Soc., vol. Ixxiv. (1904), p. 196. 



