SPONTANEOUS GENERATION 481 



view of the multitudes required to produce the observed results, be 

 ridiculed the assumption of atmospheric germs. This was one of his 

 strongest points. " Si les Proto-organismes que nous voyons pulluler 

 partout et dans tout, avaient leurs germes dissembles dans l'atmos- 

 phere, dans la proportion mathematiquement indispensable a cet effet, 

 l'air en serait totalement obscurci, car ils devraient s'y trouver beau- 

 coup plus serres que les globules d'eau qui forment nos nuages epais. 

 II n'y a pas la la moindre exageration." Recurring to the subject, 

 he exclaims, " L'air dans lequel nous vivons aurait presque la den- 

 site du fer." There is often a virulent contagion in a confident tone, 

 and this hardihood of argumentative assertion was sure to influence 

 minds swayed not by knowledge, but by authority. Had Pouchet 

 known that " the blue ethereal sky " is formed of suspended parti- 

 cles, through which the sun freely shines, he would hardly have vent- 

 ured upon this line of argument. 



Pouchet's pursuit of this inquiry strengthened the conviction with 

 which he began it, and landed him in downright credulity in the end. 

 I do not question his ability as an observer, but the inquiry 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 conditions prescribed by the experimenter himself. 

 Here Pouchet lacked the necessary discipline. Yet the vigor of his 

 onset raised clouds of doubt, which for a time obscured the whole 

 field of inquiry. So difficult indeed did the subject seem, and so inca- 

 pable of definite solution, that when Pasteur made known his inten- 

 tion 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 particularly favorable conditions. His work and his 

 culture had given strength and finish to his natural aptitudes. In 

 1862, accordingly, he published a paper " On the Organized Corpus- 

 cles existing in the Atmosphere," which must forever remain classical. 

 By the most ingenious devices he collected the floating particles of 

 the air surrounding his laboratory in the Rue d'Ulm, and subjected 

 them to microscopic examination. Many of them he found to be or- 

 ganized particles. Sowing them in sterilized 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, Montegazza, Joly, and Musset. He also 

 confirmed the experiments of Schroeder and Von Dusch. He showed 



1 " Je ne conseillerais a pcrsonne," said Dumas to his already famous pupil, " de 

 rester trop longtcmps dans ce sujet." (" Annales de Chemie et de Physique," 1862, vol. 

 lxiv., p. 22.) Since that time the illustrious Perpetual Secretary of the Academy of Sci- 

 ences has had good reason to revise this " counsel." 

 voi,. XII. 31 



