FERMENTS AND ARTIFICIAL FERMENTATIONS. 77 



circumstances, Mycodemna, vini can produce alcoholic 

 fermentation ; this is easily shown by adding it to a 

 saccharine solution, in which it soon produces fermenta- 

 tion. It appears on the surface of all alcoholic liquids 

 which are exposed to the air, when fermentation is 

 over or nearly over. Its growth is very rapid ; a few 

 cells are enough to cover the surface in the course of 

 forty-eight hours with a thin white or yellow pel- 

 licle, which is at first smooth, and then wrinkled. This 

 implies, according to Engel's estimate, that a single 

 cell has produced 35,000 others in this short time. 



Most of these different forms are probably only 

 different stages of development of a limited number 

 of species, since ferments are as polymorphic as 

 microscopic fungi. 



We have said that before they are found in the 

 must of wine or fruits, the ferments fasten in a 

 dormant state on the epidermis of the fruit, by which 

 means they are introduced into the liquid about to be 

 fermented. We see how the spores are transported 

 through the air until they rest on the downy surface 

 of a drupe or berry. But it has been asked what 

 becomes of this ferment between last year's vintage 

 and the succeeding summer, and in what way it 

 passes the winter. 



According to Hanson's researches, Sacch. apiculata, 

 which is, for instance, found upon gooseberries, is 

 washed off them by the rain, dispersed by the wind, 

 and falls to the ground with the fruit, where it 



