These include the work of Francesco Redi, who in 1668, proved that no maggots appeared in meat when flies were prevented from laying eggs; Lazzaro Spallanzani, who in 1768, showed that microorganisms could not appear in flasks of boiled broth left sealed; and Louis Pasteur's experiments in 1862, which disproved that organisms such as bacteria and fungi appear in nutrient rich media of their own ac