THE QUESTION OF SPONTANEOUS GENEEATION. 95 



' The opponents of spontaneous generation assert 

 that the germs of microscopic organisms exist in the 

 air, which transports them to a distance. What, then, 

 will these opponents say if I succeed in inducing the 

 generation of living organisms, while substituting 

 artificial air for that of the atmosphere ? ' 



Pouchet then devised this ingenious experiment. 

 He filled a bottle with boiling water, hermetically sealed 

 it with the greatest care, and plunged it upside down 

 into a basin of mercury. When the water was quite 

 cold he uncorked the bottle under the metal, and in- 

 troduced into it half a litre of pure oxygen gas, which 

 is as necessary to the life of the smallest microscopic 

 organism as it is to that of the larger animals and 

 vegetables. Up to this time there was nothing in the 

 vessel but pure water and oxygen. Pouchet then in- 

 troduced a minute bunch of hay which had been 

 enclosed in a corked bottle, and exposed in a stove 

 for a long time to a temperature of more than 100 

 degrees. At the end of eight days a mouldiness 

 was developed in this infusion of hay. ' Where 

 does this come from ? ' cried M. Pouchet triumphantly. 

 Certainly not from the oxygen, which had been pre- 

 pared from a chemical compound at the temperature 

 of incandescence. The water had been equally deprived 

 of germs, since at the boiling temperature all germs 

 would have been destroyed. The hay also could not 

 have contained them, for it had been taken from a 



