Highlights in the History of Microbiology 29 



Pasteur felt that since bacteria cannot walk, they must hav.:? 

 vehicles to carry them. Dust particles provide this necessary 

 transportation. Pouchet's rebuttal is contained in this quotation: 

 "How could orerms contained in the air be numerous enough to 

 develop in every organic infusion? Such a crowd of them would 

 produce a thick mist as dense as iron." 



Undoubtedly the first air analysis experiments were those per- 

 formed by Pasteur as he added new evidence in support of his 

 dust-borne theory of microbial dissemination. He noted that when 

 he broke the tip from his flasks sealed with their infusion contents 

 while hot, air rushing into the vessels confirmed the existence of a 

 vacuum. This observation gave Pasteur an idea which he was to 

 employ later in analyzing difterent air samples. If dust carried 

 microbes, then the streets of Paris on a windv day were certainly 

 a good source of organisms. So he prepared a number of such 

 sealed flasks and opened them in the streets of the French Capitol. 

 Everv flask revealed microbial activity upon incubation. Similar 

 flasks opened in the relatively calm, dustless atmosphere of his 

 cellar showed some infusions positive for growth, while still others 

 remained sterfle. Even fewer flasks were positive when the ves- 

 sels were opened on the Jura Mountains at an altitude of 2500 feet, 

 and only one flask in 20 showed growth when the vacuum of the 

 flasks was broken in the clear air on the Mer de Glace at a height 

 of 6000 feet. Pouchet performed similar experiments, but every 

 one of his containers opened at the 9000 foot level of the Pyrenees 

 showed growth of microorganisms. Pouchet became so incensed 

 when Pasteur continued to report results supporting the dust 

 theory, that Pouchet challenged Pasteur to a duel, which never 

 materialized. Wouldn't present day science leap ahead if every 

 time research workers disagreed the issue had to be settled with 

 drawn swords? It would be a boon to the sword manufacturers, 

 but science would undoubtedly lose many brilliant scholars whose 

 adeptness with the sword was limited! 



How can these opposite results obtained by these two workers 

 be explained? The one difference in their research was the me- 

 dium employed for growing the organisms. Pasteur used sugar. 



