428 SACOHAEOMYCES APICULATUS. 



various other conditions of environment, have, however, been 

 published. An idea of the difficulties encountered in deter- 

 minations of this kind may be gathered from 268. The 

 rapid reproduction of Sacch. apiculalus in comparison with low- 

 fermentation beer yeast is shown by certain researches performed 

 by E. HANSEN (IX.) ; and these also show how one of these 

 budding fungi can retard the growth of the other when present 

 simultaneously in the same nutrient solution. Thus, for instance, 

 three Pasteur flasks were charged with beer wort ; (a) being sown 

 with 22 cells of Sacch. cerevisice per unit volume, (6) being sown 

 with the same number, along with 19 Apiculatus cells, and (c) 

 with 20 cells of this latter only. At the end of 13 days (at 

 8-io C.) the number of cells per unit volume amounted to : (a) 

 242 of /Sacch. cerevisice (the alcohol content being 6 per cent, by 

 volume) ; (6) 240 of Sacch. cerevisice and 45 of Sacch. apic. (alcohol 

 6 per cent.) (c) 791 of Sacch. apic. (alcohol 0.5 percent.). Hence, 

 in the pure culture, Sacch. apiculatus reproduced more than three 

 times as much as Sacch. cerevisice, but was greatly retarded by the 

 latter in the mixed culture. These figures of course do not afford 

 any criterion of the rapidity of growth, since, for a given increase 

 of growth, more than three Apiculatus cells must, as a rule, be 

 formed for each one of the far larger cells of the beer yeast. 

 This harmonises also with the circumstance that, in spite of the 

 larger number of cells, the sediment in the fruit juices fermented 

 by Sacch. apiculatus is much smaller, in weight and volume, than 

 that in the juices fermented by Sacch. ellipsoideus. Consequently, 

 in order^to decide whether the protoplasm of Apiculatus yeast has a 

 lower fermentative energy than that of Sacch. cerevisice or Sacch. 

 ellipsoideus, the activity per unit weight of the yeasts must be 

 compared, and not that of an equal number of cells. 



The influence of alcohol on the growth of several Apiculatus 

 races was investigated by ROHLING (I). In harmony with the 

 general low powers of resistance of these yeasts against injurious 

 influences, a small percentage of alcohol in the culture liquid is 

 sufficient to restrict reproduction considerably. When the number 

 of yeast cells per unit volume of grape must, previous to fermen- 

 tation, was = i, it had increased to 5 14 in one of the races at the 

 close of fermentation without any addition of alcohol ; but, when 

 the must contained 2.86 per cent, of alcohol, by volume, at the 

 outset, the final number was only 192, and when the initial addition 

 of alcohol was 4.62 per cent., only 88 cells were obtained. 



The particularly frequent occurrence of Apiculatus yeast on 

 berries might lead to the supposition that the juice of these fruits 

 is specially suitable for the growth of the fungus ; but comparative 

 experiments have shown that such is not the case. According to 

 MULLER-THURGAU (II.), it matters little to the development of 

 /Sacch. apiculatus whether malic acid or tartaric acid preponderates 

 in the fruit juice. 



