ORIGIN OF THE YEASTS OF WINE 215 



The question does not arise regarding the cultivated 

 yeasts, those for example which the brewer transfers 

 from vat to vat in all seasons, as has been the custom 

 for centuries, but applies only to the wild yeasts, which 

 reappear at the appointed place every year, to ferment 

 the grape crop. For the wine-manufacturer does not 



FIG. 18. Top yeast of the brewery. 

 Old. Rejuvenated. 



add yeast to his casks, and yet the ordinary fermentation 

 begins freely and actively, sometimes in 24 hours. At 

 what moment do the stems of the cluster and the newly 

 formed fruits become charged with these germs? 



Experiment has shown that this occurs late in the 

 season. As long as the grape is in the stage of verjuice 



