

PREPARATION OF EXPRESSED YEAST JUICE 461 



of producing the fermentation phenomena exhibited by the 

 expressed juice. The sediment is also free from micro-organisms 

 after standing 3-12 days in the ice chest, nothing but a protein 

 coagulum being discernible under the microscope. 



A bacteriological investigation of expressed yeast juice by 

 BUCIINER and RAPP (II.), yielded 50-100 bacterial cultures on 

 meat- water gelatin, and 4 yeast colonies on beer-wort gelatin, per 

 i c.c. of juice. The press cakes were microscopically examined 

 by H. WILL (XX.), who found : 



Empty skins. Bruised cells. Intact cells. 



In the first experiment . 55.0 per cent. 28.0 per cent. 17.0 per cent 

 In the second experiment 15.6 ,, 81.0 ,, 2.7 



In the case of such an important new discovery, it is desirable 

 to obtain confirmation by other workers ; and this has been afforded 

 by the labours of H. WILL (XXXV.), M. DELBRUCK (VII.), J. R. 

 GREEN (II.), and MARTIN and CHAPMAN (I.). After all these 

 workers had obtained negative results, the three first-named were 

 successful on a subsequent occasion, so that only Martin and 

 Chapman really failed to obtain positive results. On the other 

 hand, very satisfactory fermentations with expressed yeast juice 

 were obtained by WROBLEWSKI (I.), AHRENS (I.), A. STAVEN- 

 HAGEN (I.), MACFADYEN, MORRIS and ROWLAND (I.), and by 

 HARDEN and YOUNG (I.). Ahrens wrote : " When once we had 

 acquired the technique of the method, we invariably obtained a 

 highly efficient juice ; and whereas, at first, we could not get any 

 useful, positive results, we never failed afterwards." 



In addition to the Buchner-Hahn method there are several 

 others. In the first place, E. BUCHNER (X.) himself tried to 

 recover the juice by the aid of liquid air, or by trituration with 

 solid carbon dioxide, equal quantities of yeast and solid carbon 

 dioxide being triturated for half an hour, and the liquid drawn off 

 by aspiration. A yield of 20 per cent, was obtained. ALBERT (I.) 

 also obtained a fermentative extract from permanent yeast by 

 trituration with sand, kieselguhr and with an addition of water 

 containing 10 per cent, of glycerin, followed by pressing. A 

 new method of preparing yeast juice was worked out by MAC- 

 FADYEX, MORRIS and ROWLAND (I.), by subjecting the yeast to a 

 number of rapid shocks in presence of particles of silver sand in a 

 special apparatus. By this treatment none of the cells remain 

 unbroken. The yeast was kept cool with the aid of brine at a 

 temperature of - 5 C. A yield of 35 per cent, of juice was 

 obtained. MARTIN and CHAPMAN (1.) recovered the juice by 

 centrifugalising, instead of by pressure. 



Other workers endeavoured to obtain extracts rich in protein 

 or extractives, instead of those with fermentative power, and 

 attained their end by means of energetic plasmolysis. Thus, C. 

 J. LINTNER (III.) recovered cell juice with salts, M. HAHN and 



