STUDIES ON FERMENTATION. 183 



as we have showu, it is absolutely necessary for the juice to 

 come into contact with the surfaces of the fruit, so that the 

 ferment may be mixed with it, and so produce subsequent 

 fermentation. Therefore, although we may apply the term 

 spontaneous ferment to the ferments of fruits, we intend that 

 expression to apply in this paragraph solely to those ferments 

 that are generated in a saccharine liquid, in which, by previous 

 boiling, we have destroyed all ferment germs, and which, 

 nevertheless, enters into fermentation after being exposed in 

 free contact with air. In such a case it is entirely from the 

 particles of dust floating in the air that the ferment germs that 

 appear in the liquid are derived. Such are typical spontaneous 

 fermentations, and it is of the ferment so obtained that we are 

 about to speak. 



In the course of the researches which we undertook in order 

 to ascertain whether mycodei'nia vini, or vinous efflorescence, 

 became transformed, in the case of beer, into actual alcoholic fer- 

 ment — researches which were the more protracted and varied in 

 consequence of their leading to the condemnation as erroneous, 

 on the faith of new and more precise experiments, such as 

 those given in Chap. IV. § 2, of that transformation, in which 

 we had for long believed — we had occasion to observe several 

 spontaneous fermentations of this kind in various saccharine 

 liquids. We then proceeded to describe our method of con- 

 ducting the experiments. Having brought about the develop- 

 ment of a film of mycoderma vini or cerevisicB on the surface of 

 a liquid, fermented or not, we submerged that film in wort, 

 which we afterwards put into long-necked flasks, in which 

 alcoholic fermentation generally took place in the course of a 

 few days. This fermentation in no way resulted from the trans- 

 formation of the cells constituting the efflorescence into ferment. 

 The mycodermic film merely acted as a receptacle of true ferment 

 germs, wafted thither with the particles of dust floating in the 

 air of the laboratory, which germs developed in the liquid into 

 actual alcoholic ferments amongst the cells of the submerged 

 mycoderma. By conducting experiments in this manner we 



