460 Dr. A. Harden and Mr. W. J. Young. [Jan. 17, 
Maximum rate for 5 minutes. 
Glucose. | Mannose. | Fructose. 
0 0°63 0°65 0°65 
0:2 7:0 
0°5 9:1 11°7 
i 9°8 8 14, °4 
2 9°7 6°6 16 
4 4 45 14°8 
8 8°4 
16 2 °4 
Expervment 13.—A similar experiment was made with a mixture of 
20 c.c. of yeast-juice and 2 grm. of the sugar, the total volume being 
40 c.c. 
Maximum rate in 5 minutes. 
Arsenate. 
Glucose. Fructose. 
cc. 
0 i! 1:2 
0°2 4e2, 
1 iP} 1 26 °6 
2 12 °4 
3 13 °4 
5 13 °4 43 °6 
7 45 °8 
10 42 °4 
15 ‘si h 39 
In this case the optimum concentration of arsenate in the presence of 
glucose is between 3 and 5 «c., and the maximum rate is about 13°4, which 
is 134 times the normal rate. In the presence of fructose, on the other 
hand, the optimum concentration is about 7 cc., and the maximum rate 
45°8 c.c., which is 38°2 times the normal rate. 
In Experiment 12 the juice evidently contains less fermenting complex, 
and there is not such a great disparity between the optima. The maximum 
rate for glucose is 9°8 c.c., for mannose, joey less, 8 c.c., and for fructose, 
16 e.c. 
6. Nature of the Effect of Arsenate on Fermentation by Yeast-jurce. 
In considering the nature of the action of arsenate in accelerating the: 
fermentation of sugars by yeast-juice two possibilities present themselves 
In the first place the arsenate may replace the phosphate in the main reaction = 
(1) 2C gH y20¢ + 2Na2H PO, = 2COz + 2C2H.60 + 2H.O0 + CgHi04(PO.Nag)e. 
