434 SACCH AKOMYCES AP1CULATUS. 



cent. that is to say, by about 24 per cent, of the original 

 quantity and in pear juice from 0.450 to 0.265 P er cent., a 

 reduction of about 40 per cent. (In the latter case, also, more 

 alcohol was produced.) Elliptical yeasts, employed with the same 

 juices for the sake of comparison, consumed a smaller proportion 

 of fixed acids; and the greater activity of Sacch. apiculatus 

 toward these acids was also apparent in mixed cultures. Never- 

 theless, since various acids are present in fruit and grape juices, 

 and acids (e.g., succinic acid) are also formed during fermentation, 

 these experiments, though of great technical interest, are incapable 

 of affording a complete solution of the behaviour of Apiculatus 

 yeasts toward acids. This is more likely to be obtained by fer- 

 mentation experiments with liquids containing only a single 

 organic acid, and of simple, known chemical constitution. 

 SCHUKOW (II.) showed, in a single experiment, that Apiculatus 

 consumed a larger quantity of acid than the beer and wine yeasts, 

 when grown in an artificial nutrient solution containing both 

 tartaric acid and malic acid. Additional researches in the same 

 direction would furnish valuable results. Of late the behaviour 

 of various fungi toward lactic acid has been investigated by 

 MEISSNER (X.), Sacch. apiculatus being also borne in mind. These 

 experiments, however, were performed with artificial solutions, 

 lacking fermentable sugars, so that, possibly, the behaviour of the 

 organisms would be different from, that in fermenting liquids 

 more favourable to development. Whereas, in the solution con- 

 taining mineral substances, peptone and lactic acid, various 

 species of wine yeasts decomposed 70 per cent, and more of the 

 lactic acid, the diminution produced by one of the Apiculatus 

 yeasts which exhibited only very slight reproduction was only 

 0.018 per cent., or 1.5 per cent, of the initial quantity. Two 

 other races proved incapable of growing at all in the solution. In 

 fermented wine the decrease of lactic acid under the action of an 

 Apiculatus yeast was less, on the average, than with the elliptical 

 yeasts, no doubt on account of the greater restrictive influence of 

 alcohol on the former. 



The consumption of acid may also be accompanied by a pro- 

 duction of acid (both volatile and fixed), in which the Apiculatus 

 yeasts likewise play some part. Of the fixed acids, succinic acid 

 has long been known as a fermentation product, and is also pro- 

 duced by Sacch. apiculatus. In the case of the two races examined 

 by him, Amthor furnished definite proof that they produce con- 

 siderable quantities of fixed acids during fermentation, the one 

 forming 0.37 per cent, (calculated as tartaric acid), or three times 

 as much as Pasteur found in fermentation with ordinary yeast. 

 To this must also be added the amount eliminated by decomposition 

 processes. Meissner has also shown that Sacch. apiculatus can 

 produce lactic acid from succinic, malic, and citric acids, in which 

 respect it is but little inferior to the wine yeasts. Nevertheless, 



