PASTEUR, KOCH, AND OTHERS 283 



tables and meats which had been extracted by boiling, placed 

 them in clean flasks, the necks of which were hermetically 

 sealed in flame, and afterward immersed them in boiling 

 water for three-quarters of an hour, in order to destroy all 



FIG. 90. LAZZARO SPALLANZANI, 1729-1799. 



germs that might be contained in them. The organic infu- 

 sions of Spallanzani remained free from change. It was 

 then, as now, a well-known fact that organic fluids, when 

 exposed to air, quickly decompose and acquire a bad smell; 



