582 Dr. Armstrong and Prof. Armstrong. Studies on [June 13, 



active they are apparently : it is on this account that the higher alcohols, 

 chloroform and similar substances are so specially active. 



The same explanation may be given of the effect produced by neutral 

 substances in reducing the electrolytic conductivity of solutions. Moreover, 

 it has been shown in S. XX and XXYI that chemical changes are similarly 

 influenced. Thus, in the former, it is proved that the rate at which urea 

 is formed from ammonic cyanate is influenced by alcohols of the ethylic 

 series and more promoted by the higher slightly soluble alcohols than by 

 the lower easily soluble. In the latter, it is shown that the equilibrium 

 between the two isodynamic forms of fructose is affected by a variety of 

 neutral substances and that the effect produced is greater the less soluble the 

 substance. 



Preferential Retardation of the Activity of Enzymes by Compatible 

 Materials. — The effect of various substances on the hydrolysis of a-methyl 

 glucoside by a-glucase is shown in the following table : — 





Weight of 

 glucose liberated 



Percentage of glucose 

 hydrolysed 



Exp. I 



Exp. II 





grm. 



'grm. 







0-97 







„ + M/o a-methyl glucoside 



0-945 



99 







0-2 



0-2 





„ + M/5 galactose 



0-82 



0-8 





M/5 a-methyl glucoside (3 "6 grm. per 100 grm. 



2-03 





57-2 



water) 









(7-2 „ „ ) 



2-69 





37 -3 



„ + M/20 glucose 



1 -67 





46-5 



+ M/10 „ 



1 -40 





39-0 



+ M/5 „ 



0-94 





26 -0 



„ + M/5 galactose 



1 -47 





41 -0 



„ +M/20 saligenin 



1 -47 





40 -8 



It will be noticed that glucose has an effect which is out of all proportion 

 large in comparison with that produced by other materials. Galactose has 

 not nearly so great an effect though its inhibiting power is considerable 

 in comparison with that of a-methyl glucoside, which is practically without 

 influence. 



The following results obtained with the /3-glucoside salicin and the enzyme 

 emulsin are in harmony with the above conclusions : — 



