198 MICRO-ORGANISMS AND FERMENTATION. 



perature, and each containing one species, Saccharomyces 

 apiculatus will multiply to a greater extent than Sac- 

 charomyces 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 transferred to the lager cellar, the fungus 

 remains inactive in the alcoholic liquid and frequently 

 perishes. 



The most interesting phases in the life of this ferment 

 are the conditions of its occurrence in nature, which have 

 also been explained by Hansen. Microscopic investigations 

 and culture-experiments showed that in the summer the 

 ferment was abundantly developed on sweet, succulent 

 fruits (cherries, gooseberries, strawberries, grapes, plums, 

 &c.) during their ripening. On the contrary it was only 

 very exceptionally found on the same fruits so long as 

 these were unripe. Since it is found in a vigorous condi- 

 tion of budding on the above-mentioned ripe fruits, but is 

 never or only exceptionally found on other fruits, leaves, 

 twigs, &c,, it is perfectly clear that Saccharomyces apicu- 

 latus has its true habitat on the ripe fruits named. This 

 was also further proved by the fact that it always, without 

 exception, occurs in the soil under the cherry trees, plum 

 trees, vines, and other plants on the fruits of which it is 

 found; whilst, on the other hand, it was only extremely 

 seldom that it was found in the numerous samples of 

 soil from other and most diverse localities. The ferment 

 is brought on to and into the earth at such places by 

 the fallen fruit and by the rain, and the question then 

 arises does it also winter there ? The answer was obtained 

 in two ways : partly by taking numerous samples of soil 

 from these places during winter and spring these, when 

 introduced into flasks containing wort, gave in by far the 

 greater number of cases a vigorous growth of our ferment 



