306 Messrs. A. Harden and W. J. Young. [ Mar. 6, 
being found by experiment to be rather more than an equivalent of glucose. 
The mixture was incubated until this conversion had been accomplished and 
the rate of fermentation had become steady. A sample was then taken and 
boiled and the free phosphate estimated in the filtrate. The remainder was 
incubated for a further period, the evolution of gas being noted, and a second 
sample was then taken. 
A parallel experiment was carried out with yeast-juice containing the 
same amount of sodium phosphate in presence of 10 grammes of glucose per 
100 ¢.c., and the evolution of gas during the same period was observed. The 
solutions used and the results obtained were as follows :-— 
Experiment 17.—(1) 100 cc. yeast-juice+ 30 ¢.c. of a solution containing 
1°3 grammes sodium phosphate and 2°62 grammes glucose. (2) 100 c.c. yeast- 
juice+30 c.c. of a solution containing 1°3 grammes sodium phosphate and 
13 grammes glucose. 
Experiment 18.—(1) 100 ¢.c. yeast-juice + 40 c.c. of a solution containing 1°7 
grammes sodium phosphate and 3:16 grammes glucose. (2) 100 cc. yeast- 
juice + 40 c.c. of a solution containing 1°7 grammes sodium phosphate and 14 
grammes glucose. 
Solution 1 (low concentration of glucose). Solution 2 (excess 
of glucose). 
| Final Phospl CO CO i tal CO | 
Original | ina osphate | 2 2 ota 2 
| phosphate. phosphate. | produced. | equivalent.| evolved. | equivalent. COsserolvad. 
c.c. c.c. 
0 :0559 0 °1052 0 04938 10 °7 39 °8 50 °5 93 °9 
0 *1036 0°1701 0 -0665 14°6 27 “7. 42 °3 69 °2 
These experiments show that although the sum of the carbon dioxide 
evolved and that equivalent to the phosphate produced in absence of glucose is 
invariably less than the amount of carbon dioxide evolved in the presence of 
glucose, yet the difference is no greater than might be expected from a 
knowledge of the prevailing conditions, and is quite consistent with the 
view that the whole of the fermentation proceeds according to the equation 
proposed. 
(4) Influence of Concentration of Phosphate on the Course of the Fermentation. 
When a phosphate is added to a fermenting mixture of glucose and yeast- 
juice, the effect varies both with the concentration of the phosphate and 
with the particular specimen of yeast-juice employed. With low concentra- 
