300 Messrs. A. Harden and W. J. Young. [ Mar. 6, 
Cubic centi- 
E . |CO, evolved | metres of | CO; evolved Increase | CO, equiva-| Increase 
meee without phosphate | in presence due to lent to after initial 
eee phosphate. aap of phosphate.! phosphate. | phosphate. period. 
added. 
grammes. C.c. grammes. gramme. gramme. gramme. 
1 0 °484 10 Orly 0 °233 0 °132 0°101 
2 1 -280 5 1 °584 0 304: 0 ‘066 0-238 
3a 0 °422 10 0 634 0 °212 0-132 0 -080 
3b 0 °422 20 0 748 0 326 0 264 0 -062 
4 0 °440 10 1 ‘258 0°818 0 °182 0 686 
5 0-405 5 0-515 0-110 0-070 0 -040 
6 0 603 5 0 ‘735 0-132 0 -066 O ‘066 
a 0 °438 5 0 -593 0 °155 0 057 0 -098 
8 1-016 15 1 632 0-616 0-198 0 418 
C.c. c.c. Os OW, c.c. 
9 369 10 629 260 63 197 
10 337 10 569 232 56 176 
(2) Recurrence of Phosphate. 
The reason for this increase in the amount of sugar decomposed in the long 
period following the short initial period of acceleration appears to be that 
the phosphorus compound first formed, which is a hexosephosphate of the 
formula CgHi04(POsRe)2,* is slowly hydrolysed, probably by an enzyme, 
with the production of a phosphate and a hexose. The phosphate is thus 
slowly regenerated and then again undergoes the reaction, causing an 
increased fermentation in the same manner as when it was originally added. 
This recurrence of phosphate is clearly shown by the following experiment. 
A known amount of phosphate was added to yeast-juice containing glucose, 
and the mixture incubated at 25° with toluene. At the close of the initial 
period a sample was removed, boiled and filtered, and the free and total 
phosphate present in it estimated, and this process was repeated at stated 
times. The results obtained are given below, the amounts of phosphate being 
expressed in grammes of MgeP20; per 10 c.c. 
Experiment 11.—215 c.c. of yeast-juice+ 20 grammes of glucose were made 
to 375 c.c. with a solution of potassium phosphate, the amount of the latter 
being equivalent to 0°133 gramme MgeP,0, per 10 c.c. of the resulting 
liquid. 
The slight increase in the total phosphate present is due to a corresponding ~ 
degree of evaporation during the experiment. It will be seen that the free 
phosphate per 10 c.c. gradually increases from 0°021 to 0°:226, so that 0:205 
gramme is regenerated. Since the total phosphorus, expressed as phosphate in 
* Young, ‘Chem. Soc. Proc.,’ 1907, vol. 65. 
