268 LOUIS PASTEUR. 



rating the substance which causes the fermentation of 

 the must of the grape. 



' I will start for the Jura,' said Pasteur. ' In the 

 midst of my vineyard, which,' he proudly added, ' is 

 ten meters square, I will cover over some stocks with 

 an improvised frame. These stocks will go on living 

 and bearing grapes, which will ripen. It is now July. 

 At this time of year, as I have already declared, the 

 germs of the cellules which form the ferment of the 

 grape in the vats do not yet exist, either on the green 

 grapes, on the bunches, or on the vine leaves. I will 

 envelop the bunches of the stocks that are under- 

 neath the frame with a layer of cotton wool that has 

 been raised to a temperature of 150 degrees Centigrade. 

 This done, I will come back to Paris with the keys of 

 the frame in my pocket, not returning to the Jura until 

 the vintage season, at the beginning of October. I 

 predict to the Academy, that the grapes wrapped in 

 cotton wool under the frame, and which will have 

 grown ripe, may be crushed in the open air, and that 

 the juice coming from them will not be capable of 

 fermentation.' 



This prediction was fulfilled. In October, Pasteur 

 returned to the Jura, plucked off several of these 

 stocks, laden with ripe bunches, and brought them 

 with the utmost care to Paris. He hud at last the 

 satisfaction of depositing them intact on the table of 

 the Academy of Sciences. He then invited M. Berthe- 



