YliAST AT A HIGH TEMPER ATURE. 



231 



piration, as it is not the protoplasm itself which, in absence of 

 air, gains its energy by decomposition of sugar, but a soluble 

 proteid, somewhat resembling the enzymes, steps in to provide 

 this energy/" 



The supposition that this proteid is connected intimately 

 with the living protoplasm and is not merely dissolved in the 

 liquid of the vacuole will jDrobably be justified. It is an exceeding- 

 ly labile proteid and perhaps closely related to the active 

 proteids from which the yeast protoplam is built up. E. Buchner 

 believes that the yeast cells secrete the zymase through its zvalls 

 and thus the sugar would be decomposed outside the cells during 

 the process of fermentation. But this supposition goes, I think, 

 beyond the limits of the immediately admissible conclusions. It 

 is true that in certain cases a secretion of this peculiar enzyme 

 takes place, but the chief quantity will to all appearance remain 

 zuithin the cells, and there most of the sugar will be fermented.*'' 

 This deduction would not only be in better accordance with the 

 economy of living cells regarding energy but would follow also 

 from the very small quantity of zymase secreted under normal 

 conditions, and further from BucJiners own observations. He 

 left, e. g., mixture of 150 cc. expressed yeast juice with 150 cc. 

 sugar solution for three days in an ice box and although this 

 mixture contained as much as 37^ saccharose, not more than 2.1 

 gram alcohol was formed during this time. It will be of special 

 interest to test whether the fermenting power of the zymase is 

 easily destroyed by diamide, hydroxylamine, amidophenol, 

 phenylhydrazine, prussic acid, and on the other hand by cyanogen, 

 nitrous acid, formaldehyde, &c. 



I have observed great differences of the enzymes in their 

 behaviour to prussic acid, which in a concentration of 25^ will 

 easily destroy diastase, though not the proteolytic enzyme of the 

 pancreas in twelve hours. But in the behaviour to formalde- 

 hyde I observed no essential differences between various enzymes ; 



(1) Not sufficiently explained, however, is the fact that while yeast cells lose their 

 fermenting power by the action of chloroform, zymase does not, according to Biuhncr. 



(2) In the fermentation of beer-wort zymase can not be shown to exist dissolved in 

 the liquid, neither in the coagulated condition in the sediment. 



(3) O. Loc-w. PfHig. Arch. 27, 208, foot-note. 



