1905.] 



The Alcoholic Ferment of Yeast-Juice. 



419 



Table VIII. — Conversion of Phosphate into the Non-precipitable Form by 

 Yeast-juice and Glucose. 





Phosphate 

 added. 



Precipitable 

 phosphate in filtrate. 



Non -precipitable 

 phosphate in filtrate. 



1 



553 



0-066 



1 -032 



2 



0-490 



0-090 



0-832 



3 



0-250 



0-054 



-685 



4 



0-488 



0-091 



1 -040 



5 



0-495 



0-088 



0-881 



The question as to whether the entire phenomenon of the fermentation of 

 glucose by yeast-juice depends on the presence of phosphates has not yet 

 been definitely decided. The addition of phosphate undoubtedly produces 

 a larger increase t in the total fermentation than is simply due to the 

 equivalent amount of carbon dioxide evolved in the initial period. The 

 extent of this increase appears to vary very considerably with different 

 specimens of yeast-juice, but the prolongation of the fermentation is not so 

 great as is caused by boiled fresh juice. This question can only be 

 satisfactorily settled by ascertaining whether the addition of a phosphate to 

 the perfectly inactive residue obtained from a juice by filtration through a 

 gelatin filter is sufficient to restore its fermenting power in the same way as 

 the filtrate or a boiled juice. Experiments on this point are in progress, but 

 no decisive result has as yet been obtained, and all discussion of this point 

 will best be deferred until these are completed. 



Various other points of interest raised in the course of the investigation, 

 and the study of the relation of these phenomena to the fermentation of 

 glucose by living yeast, are also occupying our attention. 



A short outline of the main conclusions arrived at in the foregoing paper, 

 has been previously published in the form of two preliminary com- 

 munications, without any experimental details.* After the appearance of 

 these notes, Buchner and Antonif repeated and confirmed a number of the 

 experiments dealing with the effect of boiled juice and of phosphates on the 

 total fermentation, and with the separation of the juice by dialysis into an 

 inactive residue and a dialysate capable of rendering it active. Buchner 

 and Antoni were able, with the more stable juice at their disposal, to carry 

 out the dialysis in the ordinary way for 24 hours and in this manner to 

 confirm the results obtained by the use of the gelatin filter. Owing to the 



* ' Journ. Physiol.,' 1904, vol. 32 ; ' Proc., : of November 12 ; 'Proc. Chem. Soc.,' 1903, 

 vol. 21, p. 189, June 6. 



t ' Zeit, Physiol. Chem.,' 1905, vol. 46, p. 136. 



