FERMENTATION. 54 1 



important fact that all ripening fruit, exposed to the free 

 atmosphere, absorbed the oxygen of the atmosphere and 

 liberated an approximately equal volume of carbonic acid. 

 He also found that when ripe fruits were 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, con- 

 tinued to be exhaled by the fruits, which at the same timo 

 lost a portion of their sugar, becoming more acid to the 

 taste, though the absolute quantity of acid was not 

 augmented. This was an observation of capital importance, 

 and Berard had the sagacity to remark that the process 

 might be regarded as a kind of fermentation. 



Thus the living cells of fruits can absorb oxygen and 

 breathe out carbonic acid, exactly like the living cells of 

 the leaven of beer. Supposing the access of oxygen sud- 

 denly cut off, will the living fruit cells as suddenly die, or 

 will they continue to live as yeast lives, by extracting 

 oxygen fron the saccharine juices round them? This is a 

 question of supreme theoretic significance. It was 

 first answered affirmatively by the able and conclusive 

 experiments of Lechartier and Bellamy, and the answer 

 was subsequently confirmed and explained by the experi- 

 ments and the reasoning of Pasteur. Berard only showed 

 the absorption of oxygen and the production of carbonic 

 ;icid; Lechartier and Bellamy proved the production of 

 alcohol, thus completing the evidence that it was a case 

 of real fermentation, though the common alcoholic ferment 

 was absent. So full was Pasteur of the idea that the cells 

 of the fruit would continue to live at the expense of the 

 sugar of the fruit, that once in his laboratory, while con- 

 versing on these subjects with M. Dumas, he exclaimed, 

 *' I will wager that if a grape be plunged into an atmos- 

 phere of carbonic acid, it will produce alcohol and carbonic 

 acid by the continued life of its own cells that they will 

 act for a time like the cells of the true alcoholic leaven." 

 He made the experiment, and found the result to be what 

 he had foreseen. He then extended the inquiry. Plac- 

 ing 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 

 leraoved the plums from the jar and compared them with 



