474 ENZYMES OF YEAST. 



careful drying or by means of chemical agents, such as alcohol- 

 ether K. ALBERT (I.) or acetone ALBERT, BUCHNEE, and 

 RAPP (I.). In the last-named method the operation must not 

 be regarded as one of plasmolysis, effected by the reagent, but as 

 an extraction of moisture, the reagent penetrating the cell mem- 

 brane and the strata of protoplasm, whereby all chemical reactions 

 are arrested. 



The acetonised permanent yeast, prepared from bottom- 

 fermentation beer yeast, and known in commerce as zymin, is 

 a white and practically sterile powder, as dry as dust, and con- 

 taining 5.5 to 6.5 per cent, of water. The fermentative capacity 

 calculated for 2 grms. of the preparation, disseminated in 10 c.c. 

 of water, with 4 grms. of saccharose, and 0.2 c.c. of toluene as 

 antiseptic, fermented for seventy-two hours at about 22 C., 

 corresponds to 0.96-1.09 grm. of carbon dioxide. According to 

 ALBERT, BUCHNER and RAPP (I.), the fermentative power amounts 

 to 0.40-0.49 grm. of carbon dioxide in the first twenty-four 

 hours, 0.36-4.45 grm. during the second similar period, 0.07-0.17 

 grm. in the third period and 0-0.02 grm. in the fourth. GROMOW 

 and GRIGORIEW (I.) found that the addition of fresh zymin to 

 a sample that has already become enfeebled causes renewed 

 liberation of carbon dioxide to a greater extent than would be 

 the case if the two quantities of zymin had been employed 

 together at the outset. Hence the work of the newly added 

 zymin is facilitated by the fermentation products of the amount 

 employed at first. The preparation of acetonised permanent 

 yeast is protected by patents ; and the product itself is obtainable 

 from Anton Schroder, of 45 Landwehrstrasse, Munich. It has 

 found application for medicinal purposes, and has been used 

 experimentally for baking by KOMERS and E. von HA 0N ALTER (I.) 

 and for the detection of sugar in urine by MUNZER (I.). 



Sterile permanent yeast is suitable for further investigations 

 on alcoholase. On this account mention may be made in this 

 place of a series of questions, such as the amount of alcoholase 

 present in yeast, and the formation, stability, accumulation and 

 isolation of this enzyme. 



Of these, the content and formation of alcoholase in yeast 

 interest us more particularly. For investigations of this kind, 

 permanent yeast has proved especially adapted, since it enables 

 the total content of alcoholase to be ascertained, both previous 

 to fermentation and at any other stage. Observation has long 

 since demonstrated that the amount of alcoholase present in 

 yeast is a factor varying with the physiological condition of the 

 latter. On this point, WILL (XXXV.) expresses himself as follows : 

 "It is possible that, like the peptonising enzyme, zymase is 

 present only under certain conditions ; and it is conceivable that 

 yeast which has settled down after primary fermentation, filled 

 with reserve substances and in a certain state of quiescence, 



