310 Messrs. A. Harden and W. J. Young. | Mar. 6, 
adding in every interval of five minutes the amount of phosphate equivalent 
to the carbon dioxide evolved in excess of the normal rate of fermentation 
of the yeast-juice during the same interval of time. 
Experiment 21.—25 c.c. of yeast-juice + 2°5 grammes glucose were incubated 
at 25° in the presence of toluene until the rate became constant. A solution 
of potassium phosphate (2 mol. KzHPO. and 1 mol. of KH2PQ,) of 0°3 
molar concentration was then gradually added from a graduated pipette 
provided with a tap and passing through the cork of the fermentation flask. 
Column 2 shows the c.c. of this added in each period of five minutes, and 
column 3 the evolution of carbon dioxide during each period of five minutes. 
The normal rate of the yeast-juice, in the absence of added phosphate, was 
2 C.C. per five minutes. It will be seen that an average rate of about 15 was 
maintained for an hour and a quarter, 32 c.c. of the phosphate solution being 
added in all. 
| I. | 2 | 3. 
Cubic centimetres of Beolatonteraen 
Time phosphate solution ao d eee 
in minutes. added in , Lome 
rae eee a in each 5 minutes. 
c.c. 
5 5°0 3 °1 
10 5 a) 15 *4 
15 2:0 16 ‘2 
20 1:0 20 ‘2 
25 2°5 1 
30 5 127 
35 2°0 15 <7 
40 0:0 17 °4 
45 0:0 9°6 
50 3°0 8 °4 
55 3 °0 15 °*4 
60 3 °0 20 °-2 
65 3 ‘0 72 
70 3 ‘0 14. °8 
75 153 14°9 
Further experiments on this subject are in progress, particularly with 
respect to the relations between phosphate and coferment, and the bearing of 
these phenomena on the fermentation of sugars by living yeast. 
Summary. 
1. The addition of a phosphate to a fermenting mixture of glucose and 
yeast-juice not only produces a temporary acceleration in the rate of 
fermentation, but, in addition to this, an increased total fermentation. 
2. This last effect is due to the fact that the hexosephosphate formed during 
