DEVELOPMENT OF SOIL BACTERIOLOGY 5 



remarked: "It is strange that men should deny a Creator and yet 

 attribute to themselves the power of creating eels." But this was 

 a controversy to be settled not by ridicule but by experimental 

 evidence. 



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Q 



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b 



c^^ 







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Fig. 2. — Drawings of bacteria after Pasteur (1864) — (a) urea 

 bacteria, (b) lactic acid bacteria and yeast, (c) and (d) butyric 

 acid bacteria. 



Spallanzani answered this by cracking one of the flasks so that 

 air could enter. Decay soon set in. Even this was not sufficient 

 to overthrow a popular belief, for the claim was made that the 

 sealing of the flasks excluded the air and air was essential to the 



