300 FRAGMENTS OF SCIENCE. 



his ability as an observer, but the enquiry needed a 

 disciplined experimenter. This latter implies not mere 

 ability to look at things as Nature offers them to our 

 inspection, but to force her to show herself under con- 

 ditions prescribed by the experimenter himself. Here 

 Pouchet lacked the necessary discipline. Yet the 

 vigour of his onset raised clouds of doubt, which for a 

 time obscured the whole field of enquiry. So difficult 

 indeed did the subject seem, and so incapable of definite 

 solution, that when Pasteur made known his intention 

 to take it up, his friends Biot and Dumas expressed 

 their regret, earnestly exhorting him to set a definite 

 and rigid limit to the time he purposed spending in 

 this apparently unprofitable field. 1 



Schooled by his education as a chemist, and by 

 special researches on the closely related question of 

 fermentation, Pasteur took up this subject under par- 

 ticularly favourable conditions. His work and his 

 culture had given strength and finish to his natural 

 aptitudes. In 1862, accordingly, he published a paper 

 ' On the Organised Corpuscles existing in the Atmo- 

 sphere,' which must for ever remain classical. By the 

 most ingenious devices he collected the floating par- 

 ticles of the air surrounding bis laboratory in the Eue 

 d'Ulm, and subjected them to microscopic examination. 

 Many of them he found to be organised particles. Sow- 

 ing them in sterilised infusions, he obtained abundant 

 crops of microscopic organisms. By more refined 

 methods he repeated and confirmed the experiments of 

 Schwann, which had been contested by Pouchet, Monte- 

 gazza, Joly, and Musset. He also confirmed the ex- 



1 ' Je ne conseillerais a personne,' said Dumas to his already 

 famous pupil, <de rester trop longtemps dans ce sujet.' Annalcs de 

 Chimie et de Physique, 3862, vol. Ixiv. p. 22. Since that time the 

 illustrious Perpetual Secretary of the Academy of Sciences has had 

 good reason to revise this 'counsel.' 



