1908. ] The Alcoholic Ferment of Yeust-juice. 303 
The first of these equations does not include the fermenting complex, with- 
out which, however, the change does not occur, and it is probable that both 
the glucose and the phosphate form an intermediate association with this 
complex, which then breaks down, giving rise to the substances on the right- 
hand side of the equation, and at the same time regenerating the fermenting 
complex. 
Since free phosphate and a hexosephosphate are invariably present in the 
yeast-juice prepared by grinding yeast, it follows that at all events some 
portion of the fermentation is always clue to the foregoing reactions. During 
the initial period of rapid fermentation, as long as free phosphate is still 
present, the greater part of the change is certainly due to this reaction, 
whilst in the succeeding period of slower fermentation the constant production 
of free phosphate by the enzymatic hydrolysis of the hexosephosphate already 
formed, or by the action of proteoclastic enzymes on phosphoproteins, renders 
it equally certain that some portion of this greatly diminished fermentation 
must also be ascribed to the same reaction. 
The question at once arises whether it is not possible that the whole of the 
fermentation is due to this reaction. So far, no fact has been encountered 
which is inconsistent with this view. In previous communications™ the 
authors have shown that at least two substances are concerned in the 
production of carbon dioxide and alcohol from glucose: the ferment, which 
is thermolabile, and the coferment, which is thermostable; and, further, that 
phosphates are incapable of producing any fermentation when they are added 
to a mixture of the ferment and glucose in the absence of the coferment. 
If the theory suggested above be found to be correct, it will be necessary 
to complete this statement. Two possibilities present themselves. Hither a 
third substance, a soluble phosphate, is also necessary, and in the presence of 
the fermenting complex, made up of ferment and coferment, undergoes the 
reaction under discussion ; or the coferment may itself be a complex substance 
containing a group of unknown composition, united with the phosphoric acid 
group. The latter would then be passed on to the glucose during fermenta- 
tion, and a new group taken up from the phosphate, a continuous conversion 
of phosphate into hexosephosphate being thus effected. 
If this cycle of changes correctly represents the reaction which occurs, it 
follows that the rate of fermentation after the initial period of acceleration 
depends, in the first instance, on the rate at which phosphate is liberated 
according to equation (2). 
The most satisfactory method of testing the accuracy of this view would 
‘be to free both ferment and coferment from phosphate and materials 
* *Roy. Soc. Proc.,’ B, vol. 77, 1906, p. 405 ; B, vol. 78, 1906, p. 369. 
