EOL. | The Alcoholic Ferment of Yeast-jucce. 475 
Summary. 
1. When a suitable amount of arsenate is added to a fermenting mixture of 
yeast-juice and a sugar, it causes a large acceleration in the rate of production 
of carbon dioxide and alcohol. This enhanced rate differs from that produced 
by phosphate, inasmuch as it continues long after a chemical equivalent of 
carbon dioxide has been evolved. The arsenate, moreover, 1s found in the 
free state throughout the fermentation. 
2. The rate attained increases rapidly with addition of arsenate, until an 
optimum concentration is reached, after which it decreases, at first rapidly, 
and then more slowly. 
3. The total fermentation produced depends on the particular concentra- 
tion of arsenate employed, and may be either higher or lower than that given 
in the absence of arsenate. As the high rate produced by a suitable quantity 
of arsenate persists fora long time, very considerable increases in the total 
fermentation may be observed. 
4, Glucose and mannose are similarly affected by yeast-juice in presence 
of arsenate, whereas fructose 1s much more rapidly fermented than these 
two sugars, and the optimum concentration of arsenate in its presence is. 
greater. 
5. The increased rate of fermentation of sugars in presence of arsenate is. 
due to an acceleration of the rate of action of the hexosephosphatase of the 
juice, whereby an increased supply of phosphate is afforded. The action is 
therefore essentially different from that of phosphate, and it has been found 
that arsenate cannot replace phosphate in the fundamental reaction of 
alcoholic fermentation. 
6. Arsenate also causes a considerable increase in the rate of the auto- 
fermentation of yeast-juice, and in the rate of the fermentation of glycogen. 
This is mainly due to an acceleration of the rate of action of the diastatic 
enzyme of yeast-juice (glycogenase). 
7. The action of arsenites is similar to that of arsenates, but is much es 
marked. 
8. Both arsenate and arsenite cause total inhibition of the fermentation 
when they are present in a high concentration, but the nature of this effect 
has not been ascertained. 
