100 LOUIS PASTEUR 



which are found thus associated with amorphous dust 

 indeed the germs of microscopic living beings ? Grant- 

 ing the experiment devised by Pasteur to verify that 

 of Pouchet to be irreproachable, is Pasteur's interpre- 

 tation of it rigorously true ? In presence of the 

 problem of the origin of life, all hypotheses are pos- 

 sible as long as the truth has not been clearly 

 revealed. Truly, it might be argued, if fermenta- 

 tion be caused by germs, then the air which has 

 passed through a red-hot platinum tube cannot pro- 

 voke fermentation, or putrefaction, or the formation 

 of organisms, because the germs of these last, which 

 were suspended in the air, have lost all vitality. But 

 what right have you to speak of germs ? How do 

 you know that the previous existence of germs is 

 necessary to the appearance and development of 

 microscopic organisms ? May not the prime mover 

 of the life of microscopic organisms be some appro- 

 priate medium started into activity by magnetism, 

 electricity, or even ozone ? Now, by the passing of the 

 air through your red-hot platinum tube these active 

 powers are destroyed, and the sterility of your bulb of 

 urine has nothing surprising in it. 



The partisans of spontaneous generation had 

 often employed this apparently formidable reasoning, 

 and Pasteur thought it necessary to strengthen the 

 proof that the cotton wool through which his air had 

 filtered was really charged with germs. 



