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



Activity towards a-Methyl Glucoside of Solutions prepared by extracting 

 Dried Yeast with Solutions of various Mixtures of Monopotassium and 

 Disodiuni Phosphate. 



Solution 



Sorensen values 



Walker values 



Glucose formed 

 4 hours' action 



Glucose formed 

 21 hours' action 



j8 

 a 

 A 

 B 

 

 D 

 E 

 E 

 G 

 H 



9-3 ~| 



g .g^ > alkaline 



7 -35 J 

 6-81"| 

 6 -24 | 



4-53 \ &cid 



4-6 | 

 3-3 J 



200-0 "I 



20 f alkaline 

 2-3 J 

 1 -55^ 

 5-8 | 

 50-0 ! 

 300-0 [ acia 

 1000-0 | 

 5000-0 J 



grm. 

 nil 



0-003 

 0-16 

 34 

 0-37 

 -54 

 -47 

 0-31 

 -23 

 nil 



grm. 



nil 

 0-06 

 0-49 

 0-87 

 0-90 

 0-91 

 0-88 

 0-80 

 0-72 



nil 



Similar results obtained with other enzymes are shown in the following- 

 table : — 



Enzyme 



Hydrolyte 



Time 



in 

 hours 





Belative amounts of action in 



solutions of 





Alkalinity 



Acidity 



68 



20 



2-3 



1 -5 



5-8 



50 



300 



1000 



5000 



Maltase* ... 



Maltose 



4 



1 -6 



2-2 



2 -9 



3 -5 



3 -4 



3 -35 



3 -0 



2 -9 



0-15 



Emulsin . . . 



Salicin 



4 





0-54 



2-6 



6-2 



9-4 



11 -o 



11 -2 



10 3 



2 -0 



Aucuba leaf 



)j 



5 





0-15 



9-5 



17 -3 



24 -9 



24 -3 



17 -0 



10 -6 



nil 



powder 

















87 -6 



57 2 



36 -7 





jj ») 



j> 



24 





1 -1 



30-8 



71 -1 



89 -0 



J) 



* The yeast extract used in this experiment was a portion of that used in the experiment with 

 a-methyl glucoside. 



[Note added July 30. — A particularly instructive series of observations, 

 represented in fig. 5, were made in tbe course of our experiments with 

 urease. They illustrate the remarkable sensitiveness of the enzyme to acid 

 and alkali. 



The action of the enzyme on urea . alone is represented by Graph 1. 

 Graph 2 represents the action in presence of M/25 monopotassium 

 phosphate, Graphs 3 and 4 representing the effect produced by M/5 and 

 2M/5 solutions of this salt. It wil] be noticed that the smallest pro- 

 portion produced an acceleration of the change from the outset ; the 

 intermediate proportion at first caused a retardation, but the action soon 

 set in at a greater rate than was observed in the case of the smaller 



