152 STUDIES ON FERMENTATION. 



variety of alcoholic ferment. It happens pretty often, espe- 

 cially in the Jura, where the vintage takes place about October 

 15th, when the season is already cold and little favourable to 

 fermentation, that the wine is still sweet at the moment when 

 it is put into casks. This is especially the case in good years, 

 when the sugar is abundant and the proportion of alcohol 

 high, a circumstance which prevents the completion of fei*- 

 mentation when effected at a low temperature. The wine 

 remains sweet in cask sometimes for several years, undergoing 

 a continuous but feeble alcoholic fermentation. In such wines 

 we have always observed the presence of this peculiar ferment. 

 In form it consists of a principal stem, forming nodes at various 

 points, from which short branches arise, ending in spherical 

 or ovoid cells. These cells readily detach themselves, and act 

 as spores of the plant. It is rarely, however, that we see so 

 perfect a vegetation as we have represented, because the 

 different parts fall to pieces, as we have shown in the left 

 half of the figure." 



What is the origin of cellular plants of this remarkable 

 type ? Where and how are the ferments of the grape gene- 

 rated ? 



In Chapter III. § 3 we were on our way to a solution of this 

 question. It has been shown that fermentation cannot take 

 place in the juice of crushed grapes if the must has not come 

 into contact and been mixed with particles of dust on the 

 surface of the grapes, or of the woody part of the bunch. It 

 would, however, be sufficient that a vintage vat, of any capacity 

 whatsoever, should receive the particles of dust existing on 

 a single bunch in some cases, on even a single grape, for the 

 whole mass to enter into fermentation. 



What, then, we must ask ourselves, is the nature of these 

 particles of dust ? On September 27th, 1872, we picked from a 

 vine, in the neighbourhood of Arbois, a bunch of grapes, of the 

 variety called le noirin. The bunch selected, without any 

 injury to a single grape, was brought to our laboratory in a 

 sheet of paper that had been previously scorched in the flame of 



