246 MICRO-ORGANISMS AND FERMENTATION. 



quality of the wine and must, but also checks the fermentation 

 and thus gives rise to disease. 



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 have shown that in summer the ferment was 

 abundantly developed on sweet, succulent fruits (cherries, goose- 

 berries, strawberries, grapes, plums, etc.) 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 condition of budding on these ripe fruits, but is 

 never or only exceptionally found on other fruits, leaves, twigs, 

 etc., it is perfectly clear that Saccharomyces apicidatus has its 

 true habitat on ripe fruit. This was 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 carried into the earth at such places by the fallen 

 fruit and by rain, and the question then arises whether it also 

 winters 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 contain- 

 ing wort, gave a vigorous growth of our ferment in the great 

 majority of cases partly by introducing, with every precaution, 

 cultures of Saccharomyces apiculatus into the soil and leaving 

 them during the winter. In the spring and early summer the 

 soil was again examined, and culture experiments proved that 

 the ferment was still alive in all the samples. Thus, it was 

 proved that the ferment can winter in the soil, and it had 

 previously been shown that it practically only occurs at the 

 stated places in the soil. In some more recent experiments 

 of HANSEN'S, vigorous growths of the ferment in well-closed 

 Chamberland filter-tubes were placed below the surface of the 

 earth. Three years later, the contents of the tubes were 

 introduced into sterilised wort, and a vigorous development of 

 the ferment was obtained. Its life period may thus extend 

 beyond a year. 



