ALCOHOLIC FERMENTS. 245 



capable of exciting alcoholic fermentation in beer-wort ; the 

 fermentation in this liquid is, however, a feeble one, only 1 per 

 cent, by volume of alcohol being produced, whilst Saccharomyces 

 cerevisice (bottom-yeast) under the same conditions gives 6 per 

 cent. This arises from the fact that Sacch. apiculatus cannot 

 ferment maltose. HANSEN also found that it does not secrete 

 invertase. On the other hand it excites a vigorous fermentation 

 in 1 5 per cent, and 1 per cent, solutions of dextrose in yeast- 

 water, and in one experiment as much as 3 per cent, by 

 volume of alcohol was formed. After three months the liquid 

 still contained sugar, whilst the amount of alcohol had not 

 increased during the last one and a half months. The fungus 

 was thus unable to complete the fermentation. In another of 

 HANSEN'S experiments as much as 4*3 per cent, by volume of 

 alcohol was produced. 



It was found from experiments, in which a mixture of this 

 fungus with Saccharomyces cerevisice was grown in beer-wort, 

 that it was crowded out by the latter, being the weaker 

 species, although it retarded the Sacch. cerevisice to no small 

 degree. 



In flasks with the same beer- wort, and at the same tempera- 

 ture, each containing one species, Saccharomyces apiculatus will 

 multiply to a greater extent than Saccharomyces cerevisice in a 

 given interval of time. 



At the critical time of the year, the ferment, if present in 

 the wort in considerable quantities, may exist for a length of 

 time side by side with Saccharomyces cerevisice, and will no 

 doubt retard its action a little ; but when the beer is trans- 

 ferred to the lager cellar, the fungus remains inactive in the 

 alcoholic liquid and frequently perishes. 



According to WILL, the fungus frequently occurs in slight 

 traces in low-fermentation beer-yeast ; it may be caused to 

 multiply more freely by treatment with tartaric acid, and 

 is, thus, easily found by microscopical examination. He 

 found differences in the pure cultures of apiculate-yeasts, for 

 some develop a strong bouquet resembling an amyl-ester in 

 wort, whilst others produce a peculiar mouldy smell. 



MUELLER-THURGAU and WORTMANN regard the fungus as 

 injurious to wine, for it not only directly prejudices the 



