Oil Expressed Yeast-cell Plasma (Bnchner's " Zymase"). 265 



plasm (anabolism) ; and (2) a breaking clown of this complex material 

 into simpler products, of which carbon dioxide and alcohol are the 

 constant and principal constituents (katabolism). May it not be that 

 after the expression of the cell-juice from the cell the same series of 

 actions continues to take place, at least for so long a time as the 

 rapidly changing and unstable cell-juice remains in a condition ap- 

 proximately identical with that in which it existed in the living cell ? 

 If this hypothesis be admitted, then the varying activities of the juice 

 are at least partly explicable, for if we designate by x the hypothetical 

 protoplasmic constituent of the cell with which the sugar combines, 

 then we may imagine the processes which take place in the expressed 

 cell-juice (in which we assume x to continue to exist) to be somewhat 

 as follows : . 



(a) In the case of auto-fermentation the x-sugar combination, built 

 up during the life of the cell, continues to decompose, after the ex- 

 pression of the juice, yielding carbon dioxide and alcohol. 



(b) In the case of the disappearing sugar, the formation of the 

 X-sugar combination continues to a certain point, depending on the 

 activity of the juice, but the decomposition of this combination comes 

 to an end before the whole of the sugar has been liberated in the form 

 of carbon dioxide and alcohol. In the case of a very active juice we 

 may imagine this process to continue until practically the whole of the 

 combination has been decomposed. In the case of a weak juice, the 

 building-up process takes place more rapidly than the breaking-down 

 process, and, consequently, when the activity of x ceases, there remains 

 an excess of sugar in the form of the x-sugar combination. 



We are continuing our investigations with the yeast-cell plasma, and 

 shall hope to communicate our further results to the Society in due 

 course. In the meantime it may be convenient to briefly summarise 

 the results we have already obtained, which so far appear to be leading 

 us in the direction not of an enzyme explanation of the process, but 

 rather of a theory which refers the phenomenon to the vital activity 

 of the yeast-cell protoplasm. 



(1.) The top-yeast of English breweries yields, by suitable treat- 

 ment, a cell- juice which possesses the transient power of 

 decomposing sugar into alcohol and carbonic acid. 



(2.) The amount of gas formed by an actives juice is as great as, or 

 even greater than, that found by E. Buchner. 



(3.) The cell-juice as prepared by us undergoes a very considerable 

 auto-fermentation, in some instances exceeding that given 

 by a mixture of the same juice and cane-sugar. 



(4.) A moderate dilution (1 : 2) with water or physiological salt 

 solution practically stops all fermentative activity. 



(5.) Only with a very active cell-juice does the ratio between the 



