582 



Messrs. E. Beard and W. Cramer. 



adsorption. With two other preparations no evidence of adsorption was 

 obtained. The following experiment is given as an example : — 



Experiment H. 20.5.14. Invertase F, 23.4.14, 25 per cent. 

 Kept for 20 hours at room temperature, (1) in contact with beads, and 

 (2) alone as control. 1 c.c. of each added to 10 c.c. sucrose solution, 

 10 per cent. Digested at room temperature. 



Hours. 



Contact invertase. 



Control. 



o" ■ 



+ 5-77 



+ 5-77 



18 



+ 3-98 



+ 3-84 



23 



+ 3-53 



+ 3-35 



29 



+ 2-91 



+ 2-79 



45 



+ 1-76 



+ 1-68 



90 



-0 31 



-0-36 



This experiment should be compared with the results obtained in Experi- 

 ment D, in which the same preparation of invertase was used. In this 

 experiment the inhibition produced by increasing the surface disappeared 

 again when the surface was reduced to the dimensions of the control. 



The same absence of adsorption was observed with a second preparation of 

 invertase. This preparation showed the usual inhibition of its action by 

 surface tension, and as in the previous case this inhibition disappeared in two 

 experiments when the factor of surface tension was removed. In a third such 

 experiment in which less invertase was used the inhibition persisted 

 partially. 



General Remarks. 



The observations demonstrate that the action of invertase on cane sugar is 

 retarded by increasing the surface of the system. They show further that 

 this retardation is due partly to a surface concentration effect: the surface- 

 active ferment is driven into the surface and thus prevented from combining 

 with the surface-inactive cane sugar. If one looks upon the combination of 

 substrate and enzyme as a surface concentration effect, as Bayliss does, one 

 can readily understand that this combination can be inhibited by the same 

 force acting in the opposite direction, so that these observations ■ form 

 incidentally a confirmation of the conception formulated by Bayliss. 



A question which cannot yet be answered with certainty is whether the 

 retardation observed in these experiments can be explained entirely as a 

 surface concentration effect, or whether surface tension acts also by retarding 

 the chemical process faking place in the substrate, that is, the second phase of 

 ferment action. That surface tension retards certain chemical processes, for 



