Reproduction of Vegetal Cells. 237 



but so at bottom, as shown by Schleiden and Schwann, are all living 

 organisms. Cherries, apples, peaches, pears, plums and grapes, for 

 example, are composed of cells, each of which is a living unit. " "In 

 1821, the celebrated French chemist, Berard, established the important 

 fact that all ripening fruits exposed to the free atmosphere absorb the 

 oxygen of the atmosphere, and liberate an approximately equal volume 

 of carbonic acid. He also found that when ripe fruits are placed in a con- 

 fined atmosphere, the oxygen of the atmosphere was first absorbed and an 

 equal volume of carbonic acid given out. But the process did not end here. 

 After the oxygen had vanished, carbonic acid in considerable quantities 

 continued to be exhaled by the fruits, which at the same time lost a 

 portion of their sugar, becoming more acid to the taste, though the 

 absolute quantity of the acid was not augmented." Here is a process 

 which imitates fermentation to this extent, that the cells of the fruit 

 respire, as do the cells of yeast, but being at first in contact with the 

 atmosphere they get their oxygen from it, and exhale it with carbon 

 derived from their own decaying tissues. When the amount of this free 

 oxygen, or oxygen from the open air, is limited by the fruit being shut 

 up in some close receptacle, as, for example, an air-tight barrel, the 

 cells will proceed to breathe up all the free oxygen in the barrel, 

 replacing it with carbonic acid ; and when it is all gone they will not 

 die but they will continue their respiration by extracting the oxygen 

 in the sugar of the juices by which they are surrounded in the fruit. 

 This last operation is the same as that performed by the yeast plant 

 from the first. It gets its oxygen from the sugar in the wort and does 

 not breathe the free oxygen at all. It was finally proved by Lechartier 

 and Bellamy that the last action of fruit cells, after deprivation of free 

 oxygen, produced alcohol. Pasteur confirmed this discovery by fur- 

 ther experiments. He placed grapes in an atmosphere of carbonic 

 acid, ' ' and they produced alcohol and carbonic acid by the continued 

 life of their own cells. " Then he tried it on plums. Twenty-four were 

 placed under a bell-jar filled with carbonic acid, and twenty-four similar 

 plums were placed outside the jar 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 uncovered fruits had 

 become soft, watery and very sweet ; the others were firm and hard, 

 their fleshy portions not being at all watery. They had moreover lost a 

 considerable quantity of their sugar. They were afterwards bruised and 

 the juice was distilled. It yielded six and a half grammes 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 ordinary alcoholic leaven be found. As previously proved 

 by Lechartier and Bellamy, the fermentation was the work of the living 



