47 o ENZYMES OF YEAST. 



fifths by 0.24 per cent, in the case of active juice. WROB- 

 LEWSKI (IV.) also investigated the influence of hydroxylamine 

 hydrochloride, and found that an additional 0.65 per cent, extin- 

 guished the fermentative power of the juice. 



Other antiseptics that have found extensive use in fermenta- 

 tion experiments are chloroform, thymol and toluene (see p. 247, 

 vol. ii.). Now chloroform, though applicable for this purpose, 

 causes a slight premature separation of proteids. Thymol is better, 

 but is surpassed by toluene, which latter has also been largely 

 employed by E. FISCHER and P. LINDNER (II.). Both of them 

 possess sufficient antiseptic power. R. ALBERT (I.) claimed that 

 higher fermentation values are obtainable in presence of thymol 

 than with toluene, but the accuracy of the previous statement was 

 afterwards confirmed by BUCHNER (VII.). In the experiments of 

 MACFADYEN, MORRIS and ROWLAND (I.) on the influence of anti- 

 septics on yeast juice fermentation, the results were so contradic- 

 tory in presence of sugar, that the authors admitted the desir- 

 ability of further experimentation on this point, which task was 

 afterwards undertaken by HARDEN and YOUNG (I.). 



Glycerin and saccharose in large quantities also restrict 

 development, living organisms either dying off quickly or at 

 least losing their reproductive power in strong solutions of 

 glycerin. BUCIINER (X.), however, found that fermentation with 

 yeast juice still continued vigorously, even when the total content 

 of glycerin or saccharose attained 45 per cent. 



The influence of various quantities of sugar on the progress of 

 yeast- juice fermentation may also be dealt with in this place. 

 BUCHNER and RAPP (VII.) found that the quantity of carbon 

 dioxide liberated by yeast juice attained the maximum in presence 

 of a large addition of sugar (3040 per cent.). Conversely, a 

 small quantity of sugar (5-15 per cent ) must be selected when the 

 fermentation is desired to terminate early. MACFADYEN, MORRIS 

 and ROWLAND (I.) obtained diametrically opposite results, the 

 erroneous character of which, however, was pointed out by 

 HARDEN and YOUNG (I.). 



Finally, alcohol must be mentioned as an antiseptic, and also 

 as a precipitant. Experiments in this connection with yeast juice 

 were carried out by HERZOG (I.), WROBLEWSKI (IV.) and BUCHNER 

 and ANTONI (I.). The first and two last-named of these workers 

 found that the fermentative action of yeast juice on sugar is 

 diminished as the amount of added alcohol is increased. The 

 fermentative power of the juice, however, was not finally extin- 

 guished by 1 5 per cent, of alcohol ; and it would seem as though 

 the limit of the production of alcohol in cell-less fermentation 

 were higher than with living yeast cells (see also p. 240, vol. ii.). 

 According to the researches of Wroblewski the addition of 10 

 per cent, of alcohol restricts fermentation, whilst 20 per cent, 

 arrests it completely. 



