458 Dr. A. Harden and Mr. W. J. Young. [ Jan. 17, 
concentration of arsenate employed. This rate is maintained for a varying 
time, according to the amount added, and then slowly falls off until 
ultimately fermentation ceases. 
When the concentration of arsenate 1s comparatively high, fermentation 
ceases much sooner than in the absence of arsenate, and this appears to be 
due to some direct action on the fermenting complex, similar to that which 
was observed by Buchner as resulting from the addition of potassium arsenite, 
and which is discussed later on. When, on the other hand, a small concen- 
tration of arsenate is used a high rate is produced, fermentation continues for 
a longer period than in the absence of arsenate, and a greatly increased total 
fermentation results. The total amounts of carbon dioxide and alcohol pro- 
duced therefore depend on the particular concentration of arsenate employed, 
and may be either higher or lower than that given by the juice in absence of 
arsenate. 
Experiment 10 is a typical example of the phenomena observed when a 
moderate quantity of arsenate is used, while Experiment 11 exhibits the 
effect of variation of concentration of arsenate both on the rate and the 
total fermentation. 
Experiment 10.—Parallel experiments were made with juice alone, and in 
the presence of arsenate, the solutions having the following compositions :— 
1. 20 cc. yeast-juice+15 c.c. sodium bicarbonate + 5 c.c. arsenate. 
2. 20 c.c. yeast-juice + 20 c.c. sodium bicarbonate. 
Each solution contained 4 grm. of glucose. 
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1 2. 
Time. 
Rate per 5 minutes.| Total evolved. | Rate per 5 minutes.| Total evolved. 
| | 
he c.c. | c.c. 
15 9°5 2°1 
30 13 2°1 
45 14 °2 1°9 
1 13 °9 142 °5 1°8 22 °2 
1 15 12 °8 1°6 
1 30 11 °9 1°5 
2 9°8 288 1°2 39 °5 
4, 3 °4 436 0°9 65 ‘2 
6 ioe | 498 0°7 85 
10 0-2 544 0 ‘41 108 
14 2 i 550 0°33 122 
35 0 133 
It will be seen that in the presence of arsenate (1) the maximum rate is 
attained in about 45 minutes, and amounts to 14:2 c.c. per 5 minutes; the 
total carbon dioxide evolved is 550 c.c., and fermentation ceases in about 
