28 Microbes and You 



Useful applications of Spallanzani's discovery were made by 

 Nicholas Appert (1750-1841), a French confectioner, in 1810 when 

 the French government offered 20,000 francs to the first person 

 who could perfect a method for preserving food. He founded the 

 modern canning industry when he demonstrated that food placed 

 in sealed containers and boiled for suitable time periods could be 

 stored indefinitely without spoilage. Appert did not try to explain 

 how this technic worked, but Joseph Gay-Lussac (1778-1850) 

 stated that air was necessary before fermentation and spoilage 

 could occur. Since Appert's containers were sealed when hot, a 

 vacuum was created, and both Joseph Priestley (1733-1804) and 

 Antoine Lavoissier (1743-1794) had previously contended that 

 oxygen, a constituent of air, was essential for life. 



In spite of mounting evidence that microbes must have parents, 

 Felix-Archimede Pouchet (1800-1872), a famous naturalist and 

 member of the French Academy of Sciences, lead concerted attacks 

 in support of the theorv of abiogenesis. The Academy had made 

 an offer in 1860 to anyone who could, by scientific methods, pro- 

 vide indisputable proof one way or the other on the question of 

 spontaneous generation. When Pouchet gave a paper before the 

 Academy presenting his views, many influential scientists rallied 

 to his support and Louis Pasteur was compelled to make public his 

 opposite point of view. Pasteur insisted that air contained the 

 necessary spark that reproduced cells. Microbes ride through the 

 air on dust particles, and he insisted that a dust-free atmosphere 

 harbored no microbes. We know today, however, that droplets 

 expelled from the nose and throat of man and lower animals can 

 also contain bacteria, even in the absence of dust particles. 



An English physicist, John Tyndall (1820-1893), added support 

 to Pasteur's claims when he demonstrated that an open vessel con- 

 taining a fermentable infusion would remain sterile when placed 

 in a dust-free, or optically empty atmosphere within a chamber. 

 By passing a beam of light through his chamber, Tyndall was able 

 to see whether motes were dancing in the light beam. If no motes 

 were evident to the eye, he found that there was no growth of 

 organisms in his infusions. 



