PASTEUR, KOCH, AND OTHERS 283 
tables and meats which had been extracted by boiling, placed 
them in clear 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 
Fic. 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; 
