BUFFON, NEEDHAM, SPALLANZANI, ETC. 89 



human mind sees simply: it is experiment alone which 

 leads it to simplification by ways which are sometimes 

 very tortuous. But to attain that end it is necessary 

 that the mind allow itself to be guided, and that it forget 

 its conceptions and its formulas. Nature is kindly; it 

 is we who picture her as bristling and sulky! 



In the domain of spontaneous generations, experiment 

 had been introduced for the first time in 1748 by an Irish 

 Catholic priest, Needham, whose active faith did not 

 prevent him from believing in an actual creation, that of 

 the animalculse of infusions. In order to prove this, he 

 had employed a mode of investigation destined to play 

 a great role in the controversies on the question. He had 

 enclosed some putrefiable substances in well-corked flasks 

 which he had then heated by plunging them into hot 

 ashes. The heat, he said, must kill all the living germs, 

 visible and invisible, which may be introduced into the 

 flasks, for none are known which resist boiling water. 

 Now, as my closed flasks withdrawn from the ashes be- 

 come clouded in a few days, and are peopled with micro- 

 scopic organisms, I am assisting at a phenomenon of 

 creation at the expense of dead matter, that is at a 

 spontaneous generation. 



These experiments, accepted for a long time without 

 question, met in 1765 a redoubtable critic in another abbe, 

 the illustrious Spallanzani, who, by repeating the same 

 experiments, with only the precaution of heating the 

 closed flasks longer than Needham had done, suppressed 

 all production of Infusoria. Therefore, he concluded, 

 Needham did not heat enough, and as it was for him to 

 prove his theory, which, besides, is in disagreement with 

 the facts of science, it vanished of its own accord, the 

 only fact on which it could rest having been shown to be 

 inexact. 



Not at all, replied Needham, although with much 



