1908. | The Alcoholic Ferment of Yeast-juice. 311 
the period of temporary acceleration is continually hydrolysed by an enzyme, 
with production of free phosphate, which again enters into reaction and thus 
brings about an increased fermentation. 
3. It appears probable that the presence of phosphate is essential for the 
,alcoholic fermentation of glucose by yeast-juice, the reaction which occurs 
being the following :— 
(1) 2CsHiz0¢+ 2ReHPO, = 2CO.+ 2C2H,0 + CeH904(POsRe)2 + 2H20. 
This reaction is only realised in the presence of the ferment and coferment 
discussed in previous communications, phosphate alone being unable, in the 
absence of coferment, to bring about fermentation in a mixture of ferment 
and glucose. 
The hexosephosphate thus formed is then hydrolysed : 
(2) CgHip04 POsRe)o+ 2H20 = CgH1206+ 2R2HPO,. 
The rate at which this second reaction occurs determines the rate of 
fermentation observed when glucose is fermented by yeast-juice. 
4, An optimum concentration of phosphate exists which produces a 
maximum initial rate of fermentation. Increase of concentration beyond 
this optimum diminishes the rate of fermentation. 
ho 
on) 
VOL. LXXX.—B 
