SPONTANEOUS GENERATION 93 



liquid became turbid, and teeming with living or- 

 ganisms. "What reply," asks Pasteur, "do you 

 make to this experiment? Will you claim that the 

 cotton, being an organic substance, generates life?" 

 Even this possibility was met. Pasteur replaced 

 the cotton by the purely mineral fiber of asbestos, 

 and obtained precisely the same results. These 



Fig. 8. Flask with Sealed Neck Partly Filled with 



Boiled Infusion 



were crucial and clear-cut experiments and their 

 answer was decisive. 



Pasteur's instinct for thoroughness led him to 

 make a detailed study of the atmosphere of dif- 

 ferent localities, in order to ascertain whether or not 

 it possessed uniformly the same power of generating 

 life. In this investigation, he used small straight- 

 necked flasks (Fig. 8), partly filled with an infu- 



