206s Dr. A. Harden and Mr. W. J. Young. [Jan. 17, 
C.c. evolved in preceding 5 minutes. 
Time after addition of arsenate, 
in minutes. 
1. 2. 
5 2°8 1 4 
10 PHOT 1 *4 
15 2°5 1:2 
20 2°3 1:0 
25 2°3 _ 
65 2°4 1°3 
90 2°2 1°3 
115 1°84 1 °04 
4 
° 
= 
2 
— 
rer 
Bp 
| 
_ 
Or 
as 
ay 
Go 
| 
| 25'8 
| 
Whether the arsenate also accelerates the action of the zymase has not | 
been decided with certainty. If this were so, the rate of fermentation 
attainable by the proper mixture of arsenate and phosphate would be greater 
than that given by phosphate alone. Since, however, the rate of fermenta- 
tion in presence of phosphate falls off with diminishing concentration of 
this salt extremely rapidly and according to a law which has not yet been 
ascertained, it is impossible at present to institute an accurate comparison 
between the velocity constants of the two reactions. It may, however, be 
noted that cases have been observed in which the evolution of gas in five 
minutes was greater in presence of a certain quantity of arsenate than could 
be obtained with phosphate alone. 
7. Effect of Arsenate on the Auto-fermentation of Yeast-jurce. 
When arsenate is added to yeast-juice which is undergoing auto-fermenta- 
tion, a very considerable rise is produced in the rate of evolution of carbon 
dioxide; the rate attained is, however, much lower than that produced in 
presence of excess of glucose. The extent of this enhanced auto-fermenta- 
tion is shown by the following (Nos. 1 and 2), whilst the effect of the 
same quantity of arsenate in presence of excess of glucose is given in 
columns 3 and 4. 
LHxpervment 14.—Four solutions were incubated, all being made to the 
same volume of 30°5 c.c. 
1. 20 c.c. yeast-juice+10°5 c.c. water+0 c.c. arsenate. 
2. 33 3 he 10 3) =P 0-5 ” 
as p ‘3 OO ae +0 ¢ +2 grm. glucose. 
4. ”» 39 ain 8°8 9) =F 0-5 re) ++ 2 bP) 
The following rates were observed :— 
