FERMENTATION 279 



made the experiment, and found tlie result to be what he 

 had foreseen. He then extended the inquiry. Placing 

 under a bell-jar twenty-four plums, he filled the jar with 

 carbonic acid gas; beside it he placed twenty-four similar 

 plums uncovered. At the end of eight days, he removed 

 the plums from the jar, and compared them with the 

 others. The difference was extraordinary. The uncov- 

 ered fruits had become soft, watery, and very sweet; the 

 others were firm and hard, their fleshy portions being not 

 at all watery. They had, moreover, lost a considerable 

 quantity of their sugar. They were afterward bruised, 

 and the juice was distilled. It yielded six and a half 

 grams of alcohol, or one per cent of the total weight of 

 the plums. Neither in these plums, nor in the grapes first 

 experimented on by Pasteur, could any trace of the or- 

 dinary alcoholic leaven be found. As previously proved 

 by Lechartier and Bellamy, the fermentation was the work 

 of the living cells of the fruit itseK, after air had been 

 denied to them. When, moreover, the cells were de- 

 stroyed by bruising, no fermentation ensued. The fer- 

 mentation was the correlative of a vital act, and it ceased 

 when life was extinguished. 



Liidersdorf was the first to show by this method that 

 yeast acted, not, as Liebig had assumed, in virtue of its 

 organic^ but in virtue of its organized character. He de- 

 stroyed the cells of yeast by rubbing them on a ground 

 glass plate, and found that with the destruction of the 

 organism, though its chemical constituents remained, the 

 power to act as a ferment totally disappeared. 



One word more in reference to Liebig may find a place 

 here. To the philosophic chemist thoughtfully pondering 

 these phenomena, familiar with the conception of molec- 



