478 ENZYMES OF YEAST. 



be extracted under such conditions, the cell walls and envelope of 

 coagulated protoplasm must be broken down before proceeding to 

 the operation of extracting the enzyme with glycerin and water. 

 ALBERT (I.) therefore allows 50 grms. of the permanent yeast to 

 dry along with 100 grms. of quartz sand, and then triturates the 

 mass with 100 c.c. of water, the liquid portion being afterwards 

 separated from the solids by means of hydraulic pressure or an 

 aspirator. Precipitation with alcohol ether furnishes 2-3 grms. 

 of a yellowish white powder, which differs from the yeast juice 

 precipitates in being readily soluble, and of being precipitable 

 again and again without appreciable loss of fermentative power. 

 With regard to these experiments, all that need be mentioned is 

 that the use of quartz sand in triturating permanent yeast is not 

 free from objection, since dry grinding for ten minutes results in 

 a noticeable diminution of fermentative power. Nevertheless it 

 is probable that further progress toward the isolation of alcoholase 

 may be accomplished in this manner, especially if loss of fermen- 

 tative power be still further prevented by discontinuing the use 

 of quartz sand, and if alcohol-ether be replaced by mixtures of 

 acetone and ether or other innocuous precipitants, provided no 

 very high degree of purity is expected in the resulting preparation. 

 The proof that the fermentative enzyme cannot be extracted 

 from sterile permanent yeast, unless the cells have previously 

 been ruptured by mechanical means, also demonstrates clearly 

 that fermentation goes on inside the yeast cells, and not externally. 

 This also follows from the circumstance that nlcoholase cannot be 

 dialysed, and that glycogen is not fermented by beer yeast until 

 the cell membranes have been broken. Hence, alcoholase is an 

 endoenzyme. 



321. The Position of Aleoholase with Relation to 

 the other Enzymes. 



Before considering the relative position of alcoholase to the 

 other enzymes, we will devote some attention to the discussions 

 that have attended the discovery of this enzyme. So long as the 

 separation of the fermentative enzyme from the living yeast cells 

 had not become an accomplished fact, differences of opinion 

 between scientists were readily conceivable ; but even after the 

 result in question had been achieved, an experimental solution 

 afforded of the highly important problem, and all the errors of 

 reinvestigation corrected, the doubting spirits began to advance 

 other objections. At first it was sought to ascribe the fermenta- 

 tion to micro-organisms still present in the juice; but this objec- 

 tion fell to the ground when active antiseptics were used in all 

 cell-juice fermentations, and after LANGE had shown (II.) that the 

 fermentative effect of the juice could not be produced by ten 

 times the number of yeast cells found in the crude juice. Others 



