LOUIS PASTEUR 483 



what was then supposed to be an insoluble puzzle, that 

 of "spontaneous generation." Did life, in the form of 

 corpuscles or germs, come into existence without having 

 any parents, any ancestors ? Many had debated the 

 matter, and wise men had set it aside as incapable of 

 solution, a subject for cranks, like perpetual motion. 

 This did not discourage Pasteur, nor was he willing to 

 desist when his old friend Biot warned him earnestly 

 that he was wasting his time. After a series of simple 

 but brilliant experiments he was able to prove that the 

 organisms of fermentation and decay,' which were sup- 

 posed to originate in liquids containing organic matter, 

 actually came from the air. Boil the liquids and then 

 exclude the air, and no fermentation takes place, no 

 organisms appear. Thus, after years of futile debate, 

 the matter of spontaneous generation was settled by 

 experiment. Many years before, one Spallanzani, an 

 Italian, had reached similar conclusions, but Pasteur's 

 experiments were far more varied and decisive. The 

 matter was not of merely theoretical interest : the fact 

 demonstrated by Pasteur makes possible the canning 

 industry of modern times. 



8. On the same principle, Pasteur was now able to Diseases of 

 investigate the "diseases" of wines, which cause them wmes 



to spoil on keeping. The exportation of French wines 

 had seriously fallen off on account of the difficulty of 

 keeping them in various climates. The trouble was due 

 to parasitic plants, germs, or corpuscles ; or, as we should 

 now say, yeasts or bacteria. These could be destroyed 

 by heating, and thus the difficulty was overcome. 



9. In 1865 a new calamity was ruining the silk in- Silkworm 

 dustry in France. The silkworms perished from two dlseases 

 different diseases. Pebrine caused the worms to become 

 spotted (the word signifies "peppered") and dry up like 



