1910.] The Alcoholic' F erment of Ycast-jvAce. 327 





Gas evolved. 



Oas evolved, 

 corrected for auto- 

 fermentation. 











c.c. 







15 c.c. yeast suspension 



+ 46 c.c. 



Xo. 1 



84-1 



77 '5 



b. 



15 ' 



+ 46 „ 



Xo. 2 



36-4 



29 -8 



c. 



15 ., 



+ 46 „ 



Xo. 3 



9-4 



2-8 



d. 



15 ,. 



+ 46 „ 





6 -6 





The carbon dioxide derived from the sugar produced by the enzymic 

 hydrolysis of the hexosephosphate by the zymin is therefore equal to 

 77-5- (29-8 + 2-8) = 44-9 c.c. 



Hence the sugar formed by digesting hexosephosphate with zymin is 

 readily fermentable by yeast. 



(f/) Production of carbon dioxide from hexosephosphate by yeast-juice and 

 zymin. 



It follows from the facts recounted above, which are expressed in 

 equation (2) at the commencement of the paper, that the products of the 

 enzymic hydrolysis of the hexosephosphates should be fermented by yeast- 

 juice. Since, moreover, the enzyme producing this hydrolysis, which may be 

 termed hexosephos'phatase, is present in yeast-juice, the hexosephosphate itself 

 when added to yeast-juice should undergo gradual hydrolysis and fermenta- 

 tion. The whole of the phosphorus would then be liberated as free 

 phosphate, and the carbohydrate residue would be converted into alcohol and 

 carbon dioxide. 



The following experiments show that hexosephosphate is actually 

 fermented by yeast-juice with evolution of carbon dioxide and production 

 of free phosphate : — 



Experiment 10. — Two quantities of 25 c.c. of j-east-juice were incubated at 25' in 

 presence of toluene until a steady rate of auto-femientatiou had been attained, (a) To 

 one were added 1.5 c.c. of water ; {h) To the other were added 15 c.c. of a solution of 

 sodium hexosephosphate containing phosphorus equivalent to 0 4673 gramme of MgjPjO^ 

 and therefore capable of yielding 94"3 c.c. of carbon dioxide. 



CO, evolved in 40 hours, 

 c.c. 

 a. 85 

 h. 131-8 



DiflFerence 46-8 at 19' and 762 mm. = 42-97 c.c. at N.T.P. 



Somewhat less tlian half the available carbon dioxide was therefore evolved. 



In this case the auto-fermentation of the yeast-juice was a considerable 

 fraction of the total fermentation produced in presence of the hexose- 



