“304 Messrs. A. Harden and W. J. Young. [ Mar. 6, 
‘capable of yielding phosphates under the influence of the enzymes which 
-are present, and then to ascertain whether the mixture of these purified 
materials would ferment glucose; and, further, if they did not, whether the 
-addition of a phosphate would bring about fermentation. Many attempts 
have been made to realise these conditions, but hitherto without success. 
It is obvious that if the coferment be a hydrolysable derivative of 
phosphoric acid, as suggested above, success in this direction cannot be 
anticipated. 
Some idea of the extent to which alcoholic fermentation is due to this 
recurrence of phosphate could also be gained by ascertaining the amount of 
free phosphate produced from hexosephosphate in yeast-juice in a given time 
‘in the absence of glucose, and comparing this with the amount of carbon 
dioxide evolved in the presence of glucose under otherwise identical 
conditions. 
In practice, however, two difficulties present themselves. In the first 
place, in the absence of fermentable sugar, or when the concentration of this 
is very low, free phosphate accumulates, and the rate of hydrolysis of the 
hexosephosphate is thus diminished; whereas in the presence of glucose the 
concentration of phosphate remains constant at a low value during fermen- 
tation, and the rate of hydrolysis of hexosephosphate accordingly remains at 
its maximum for a considerable period. 
This inhibitory effect of phosphate on the hydrolysis of hexosephosphate 
in the absence of all fermentation is shown in the following experiment, 
which also indicates the extent to which this hydrolysis occurs under these 
conditions. 
EHxpervment 16.—In order to avoid all fermentation, the inactive residue 
obtained by filtering yeast-juice through a Martin gelatin-filter was 
employed, and equal weights of this were incubated for 20 hours with: 
(1) water ; (2) a solution of sodium hexosephosphate free from glucose and free 
phosphate ; (3) a solution of sodium hexosephosphate + an equivalent amount 
of sodium phosphate. A solution of hexosephosphate was also incubated 
alone, the conditions of concentration and alkalinity being identical in all 
four solutions. At the expiration of 20 hours, the solutions were all boiled, 
and the free phosphate in the filtrates estimated. In the following table the 
numbers represent the weight of Mg2P,0, found. 
The numbers in the last column are obtained by adding together the 
-amount of phosphate produced separately by the incubation of the hexose- 
phosphate and the residue, and subtracting their sum from the free phosphate 
produced in the other two solutions. 
It appears from this that in this particular instance the enzymatic 
