VELOCITY OF REACTION 75 



emulsin, or maltase by the products to which they respectively give 

 rise. Consequently, for these latter enzymes, the linear period is 

 of short duration, and the logarithmic period is barely perceptible 

 owing to the rapid reduction in the rate. 



"Case IV. When the amount of enzyme and water is kept 

 constant whilst that of sugar is increased, it may be supposed that the 

 magnitude of the active system will increase until s + e reaches 

 a maximum, a definite equilibrium being established between 

 enzyme, sugar, and water, the whole of the enzyme, perhaps, becoming 

 combined with the sugar. It may be assumed that if the amount 

 of sugar be further increased, the equilibrium will remain unaffected, 

 notwithstanding that an addition of sugar is practically equivalent 

 to a withdrawal of water. 



"But if s + e remain unaltered, whatever the proportion of 

 sugar present beyond a certain minimum, a constant amount of 

 hydrolyte will undergo change in a given time, although the propor- 

 tion changed as also the value of K will decrease as the concentration 

 is increased. This conclusion is entirely in agreement with the 

 facts elucidated especially by Adrian Brown, and with my own 

 observations." 



With regard to the effects of varying the amount of enzyme, 

 E. F. Armstrong states that the weight hydrolysed in a given 

 time by varying amounts of enzyme was approximately propor- 

 tional to the amount of enzyme, provided that the amount was 

 not too large, and also that the comparison was made during the 

 earlier stages of hydrolysis before the secondary products began 

 to exert a marked influence. 



In a recent paper Bayliss has published an extensive series 

 of observations on the hydrolysis of various proteids, chiefly 

 caseinogen and gelatin, by the action of trypsin. The method 

 used by Bayliss was that of measuring the increase in electrical 

 conductivity, and it appears from his statements to be both 

 convenient in carrying out experimentally and to give reliable 

 results. 



With regard to the course of the reaction, Bayliss found that 

 the curve representing quantity converted and time, fell off con- 

 tinuously and rapidly throughout the experiment from the loga- 

 rithmic curve, the velocity constant decreasing in value to the 

 end. The form of the curve (which tends to become asymptotic 

 to the base line) shows that the velocity of reaction tends to 

 become zero, that is to say, that there is an equilibrium point with 



