272 MICRO-ORGANISMS AND FERMENTATION. 



ripening of the sweet juicy fruits (cherries, gooseberries, straw- 

 berries, grapes, plums, etc.). On the other hand, it was only 

 quite exceptionally that they were found on the unripe fruit. 

 As the organisms were found vigorously budding on the ripe 

 fruit, but never, or only very rarely on other fruit, and on 

 the leaves, branches, etc., the fact may be accepted that these 

 ripe fruits act as a true host to S. apiculatus. This was 

 further established by the observation that they are to 

 be found without exception in the soil under cherry and 

 plum trees, vines, and other fruit-bearing trees upon which 

 the organism grows, but that they are extremely seldom 

 found in samples of soil taken in other localities of a most 

 varied character. The fruit falls to the ground, and the rain 

 carries the fungus into the soil ; the problem, then, is whether 

 it is able to winter there. The answer was obtained in two 

 ways. First, numerous samples of soil were taken during the 

 course of the winter and spring at these places, and in the 

 vast majority of cases these gave a vigorous growth of the 

 organism in wort. Secondly, cultures of S. apiculatus were 

 placed with every precaution in the earth, and allowed to 

 remain throughout the winter. They were removed in the 

 spring and early summer, and culture experiments proved 

 that the organism was alive in every sample. In this way it 

 was established that the organism is able to winter in the 

 earth, just as it had been previously shown that it only occurred 

 in the soil at these particular localities. In later experiments 

 of Hansen's, vigorous growths of the organism were placed on 

 the surface of the soil in well-sealed Chamberland filter tubes. 

 Three years later the contents of these tubes were introduced 

 into sterilised wort, and a vigorous growth of the organism 

 developed. The cycle of operations may, therefore, be spread 

 over more than one year. 



It still remained to be proved whether the earth is the true 

 habitat in winter time. This was carried out as follows : : 

 Hansen examined dust in a great variety of places from 

 January to June, and also the dried fallen fruit of many trees, 

 and lastly, many kinds of excrement. These analyses gave 

 a negative result, and thus furnished the desired proof. The 

 soil under the particular fruit trees must, therefore, be regarded 



