1911. ] The Alcoholic Ferment of Yeast-jwee. 459 
12 to 14 hours. In the absence of arsenate (2), the maximum is attained at 
once and is 2:1, the total evolved is 133 cc., and the duration of the 
fermentation is about 24 to 30 hours. 
Experiment 11.—The totals evolved by equal volumes of the juice 
employed in the foregoing experiment were determined with various 
additions of arsenate, and are quoted along with the maximum rates and the 
approximate duration of fermentation. 
No. | Arsenate added. | Maximum rate. | Total evolved. | Duration of fermentation. 
c.c. hours. 
1 0 2°8 1333 24—30 
23 0°5 25 1024 55—60 
3 5 142 550 12—14 
4, 10 5 °9 | 190 °6 9—10 
5 20 | 15 47 °8 7 
| | 
4 germ. of glucose were present in each case, and it is probable that fermen- 
tation in No. 2 came to a close on account of exhaustion of the sugar. 
5. The Fermentation of Mannose and Fructose by Yeast-jwice in the Presence 
of Arsenate. 
The fermentation of mannose by yeast-juice is also accelerated by the 
addition of arsenate to about the same extent as that of glucose. In the 
case of fructose, however, a difference, similar in character to that previously 
noted in the presence of phosphate,* is also observed with arsenate, viz., the 
optimum concentration of arsenate is greater and the maximum rate 
attainable higher than in the case of glucose. 
These facts are well brought out by the results of the following two 
experiments. 
Expervment 12.—A series of different volumes of the standard arsenate 
solution were added to yeast-juice in presence of 1 grm. of the sugar in 
question, all the liquids being made up to the same volume, and the maximum 
rate attained in each case observed. 
20 c.c. yeast-juice + x c.c. arsenate + (26—2) cc, of a solution containing 
1 grm. of sugar. 
* Harden and Young, ‘ Roy. Soc. Proc.,’ B, 1909, vol. 81, p. 336. 
