480 ENZYMES OF YEAST. 



more recent ones of HARDEN and YOUNG (I.). Finally, several 

 physiological reasons may be advanced against the plasmal theory. 

 For instance, the acceptance of this hypothesis affords no explana- 

 tion of the circumstance that juice incapable of producing fer- 

 mentation should occasionally be furnished by exceedingly 

 vigorous yeast, although the hypothetical particles of plasma are 

 present in the juice, or of the fact that the fermentative enzyme 

 can be concentrated as was shown by R. ALBERT (II.), BUCHNER 

 and SPITTA (I.) and LANGE (III.)- In such case we can hardly 

 assume that an alteration of the whole protoplasm has occurred. 



In view of all these facts, and also of the behaviour of yeast 

 juice in presence of toluene and 40 per cent, sugar solution, after 

 centrifugalising, treatment in the Ohamberland filter, desiccation, 

 storage, heating, precipitation, extraction of the precipitate, ex- 

 traction of killed permanent yeast with glycerine and water, and 

 the reprecipitation of such solution, Buchner rightly concludes 

 that no living agent is present in yeast juice. Those holding 

 an opposite opinion will be obliged to furnish a new definition of 

 what is meant by " life " a course leading merely to useless 

 polemics. It is an indubitable fact that yeast juice does not 

 represent the cell in its entirety, but the cell contents freed from 

 membrane and other insoluble constituents, that is to say, a 

 product forming only part of the erstwhile living cells. To 

 assume that, under certain conditions, the parts that have been 

 separated from the living cells and are totally incapable of growth 

 will be able to continue living, is a novel and highly improbable 

 idea. On the other hand, the hypothesis that these separated, 

 soluble components of the cell have retained their activity and 

 are capable of exerting it under certain conditions, accords with 

 all existing experience and observation, and appears to be correct. 

 Moreover, it has been demonstrated that the fermentative agent 

 forms only an insignificant proportion of the soluble cell- substance, 

 that it is soluble in water ; and that it can be precipitated from 

 triturated permanent yeast, redissolved and reprecipitated pro- 

 perties that had never been expected of living protoplasm. 



We may now proceed with the comparison between alcoholase 

 and other enzymes. In the first place it must be remembered 

 that the properties of all known enzymes vary more or less 

 considerably, so that it is by no means surprising to find that 

 the more labile alcoholase exhibits points of difference from 

 other enzymes, which differences do not justify denial of its 

 enzymatic nature. Alcoholase exhibits the same properties as 

 other enzymes, including solubility in water, with or without 

 glycerine ; precipitability by alcohol, ether, or acetone ; the 

 faculty of being carried down with other precipitated substances, 

 such as calcium phosphate, precipitated protein, &c., and 

 finally, susceptibility toward chemical reagents and protoplasmal 

 poisons. Differences are exhibited to some extent in respect of its 



