430 SACCHAROMYCES APICULATUS. 



exhibited by the various races. Apart from this, Sacch. apiculatus 

 is much more sensitive than Sacch. ellipsoideus, the cells of the 

 former being generally found dead in the deposit from fermented 

 wine The fact that individual cells probably of a more vigorous 

 race occasionally exhibit considerable longevity, was proved by a 

 discovery of R. BKAUN (II.), who found living cells of Sacch. 

 apiculatus in beer containing about 8 per cent, of alcohol after at 

 least five years. MULLER-THURGAU (XXIV.) also found, in his 

 attempts to discover suitable methods of obtaining a purer 

 fermentation of fruit and grape wines, that Apiculatus yeasts are 

 killed by a quantity of sulphur dioxide (in the must) that is 

 innocuous to the elliptical wine yeasts. Both HANSEN (LVIL) and 

 KAYSER (III.) mention Sacch. apiculatus as particularly susceptible 

 to the influence of desiccation; though, on the other hand, according 

 to WILL (XXXIY.) the various races differ in this respect. A. 

 BERLESE (II.) regards the fungus as offering a powerful resistance 

 to the action of direct sunlight. The resistance of Apiculatus yeast 

 to high temperatures was examined by MULLER-THURGAU (XXV.), 

 who found, moreover, that the various races differ in this particular. 

 One of them proved to be far more susceptible to this influence 

 than the others under examination, being killed by an exposure of 

 ten minutes to 50 C. in grape juice, whereas the others were able 

 to withstand ten minutes at 55 C., and thus closely approximated 

 to the elliptical wine yeasts in this respect. The point whether the 

 growth of the races of Sacch. apicidatus is dependent on tempera- 

 ture in a different manner from that of the true wine yeasts has 

 not yet been investigated, though the matter is one of some import- 

 ance to the conduct of the fermentation (see also p. 254, vol. ii.). 



312. Fermentation Phenomena of Apiculatus Yeast. 



The fermentation set up by Saccharomyces apiculatus is in- 

 variably of the bottom fermentation type. In fruit and grape 

 juices it is often confined to a merely slight turbidity, owing to 

 the low general fermentative activity of this yeast, and also as 

 pointed out by REESS (I.) because the cells being detached and 

 not aggregated, do not offer suitable points of attachment to the 

 bubbles of carbon dioxide. 



The various races exhibit a certain uniformity in point of 

 fermentation phenomena and metabolism, though they differ 

 considerably from the true beer and wine yeasts. In this 

 connection, however, the first-named have not been examined 

 very closely. The races described by Hansen set up a vigorous, 

 though not very extensive, fermentation in a nutrient solution 

 containing dextrose (^-glucose), the resulting " head " being 

 composed of numerous fine bubbles, and not attaining the same 

 dimensions as that thrown up by Sacch. cerevisice, for instance. 

 The same behaviour toward dextrose is exhibited by Amthor's 



