The Alcoholic Ferment of Yeast-jwece. 451 
the main stem only bear three glands (1-3), appear to be impure. Such 
plants are produced by crossing the two pure forms (0) and (3-1). Type 2 
appears to be an exception, being a pure form with leaf glands (1), while 
Types 3 and 10 have only been observed in the pure (3-1) condition. Type 1 
has not been observed sufficiently to justify a definite statement. 
The Alcoholic Ferment of Yeast-juice. Part VI.—The Influence 
of Arsenates and Arsenites on the Fermentation of the Sugars 
by Yeast-jusce. 
By Artuur Harpen, F.RS., and W. J. Youne (Biochemical Laboratory, 
Lister Institute). 
(Received January 17,—Read March 2, 1911.) 
The rate of fermentation of a simple sugar by yeast-juice undergoes a 
temporary acceleration when a soluble phosphate is added.* The close 
chemical analogy which exists between phosphates and arsenates suggested 
the idea that this similarity might extend to the effect of arsenates on 
fermentation, and accordingly experiments were made to test the point. It 
was thus found that arsenates have a great effect on fermentation, but 
subsequent work has shown that it is of a totally different nature from 
that exerted by phosphates. 
I. Influence of Arsenate on the Rate of Fermentation. 
When a solution of sodium arsenate is added to a mixture of glucose, 
mannose or fructose with yeast-juice, which has attained a steady rate 
of fermentation, an immediate large increase in the rate of evolution of 
carbon dioxide is produced. The rate, as a rule, rises for a short period, 
attains a maximum, and then very gradually diminishes. A typical example 
is the following. 
Experiment 1.—The experiments throughout were carried out at 25° in 
presence of toluene, the solutions being previously saturated with carbon 
dioxide. The standard solution of sodium arsenate employed was approxi- 
mately 0°3 molar, and was prepared by dissolving 5312 grammes of 
crystallised sodium arsenate in water, and making up to 100 cc. Two 
* Harden and Young, ‘ Roy. Soc. Proc.,’ B, 1906, vol. 77, p. 410. 
