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time when, seconded by the progress of science, several 

 naturalists are endeavouring to reduce the domain of spon- 

 taneous generation or even to deny its existence altogether, I 

 have undertaken a series of researches with the object of 

 elucidating this vexed question." Pouchet, declaring that he 

 had taken excessive precautions to preserve his experiments 

 from any cause of error, proclaimed that he was prepared to 

 demonstrate that " animals and plants could be generated in a 

 medium absolutely free from atmospheric air, and in which, 

 therefore, no germ of organic bodies could have been brought 

 by air. 1 ' 



On one copy of that communication, the opening of a four 

 years' scientific campaign, Pasteur had underlined the pas- 

 sages which he intended to submit to rigorous experimentation. 

 The scientific world was discussing the matter; Pasteur set 

 himself to work. 



A new installation, albeit a summary one, allowed him to 

 attempt some delicate experiments. At one of the extremities 

 of the facade of the Ecole Normale, on the same line as the 

 doorkeeper's lodge, a pavilion had been built for the school 

 architect and his clerk. Pasteur succeeded in obtaining pos- 

 session of this small building, and transformed it into a labora- 

 tory. He built a drying stove under the staircase ; though he 

 could only reach the stove by crawling on his knees, yet this 

 was better than his old attic. He also had a pleasant surprise 

 he was given a curator. He had deserved one sooner, for he 

 had founded the institution of agreges preparateurs. Eemem- 

 bering his own desire, on leaving the Ecole Normale, to have a 

 year or two for independent study, he had wished to facilitate 

 for others the obtaining of those few years of research and per- 

 haps inspiration. Thanks to him, five places as laboratory 

 curators were exclusively reserved to Ecole Normale students 

 who had taken their degree (agreges). The first curator who 

 entered the new laboratory was Jules Kaulin, a young man with 

 a clear and sagacious mind, a calm and tenacious character, 

 loving difficulties for the sake of overcoming them. 



Pasteur began by the microscopic study of atmospheric air. 

 "If germs exist in atmosphere," he said, "could they not 

 be arrested on their way ? " It then occurred to him to draw 

 through an aspirator a current of outside air through a 

 tube containing a little plug of cotton wool. The current as it 

 passed deposited on this sort of filter some of the solid corpuscles 



assed d 



* 



