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Francesco Redi
Redi challenged spontaneous generation by conducting experiments with meat and flies. Redi placed raw meat in two sets of jars one covered with gauze and one open to the air. Maggots appeared only in the open jars where flies could lay eggs, proving that life arises from other life and not spontaneously. His conclusion was that life comes from pre-existing life, supporting biogenesis. -
John Needham
Needham boiled broth and poured it into flasks, he then sealed them after cooling, and observed the microorganism growth. Needham claimed that this was the evidence of spontaneous generation, though there was an error in his experiment, because the flask was open when before he boiled the broth and microorganisms could've entered. Hi experiments seemed to uphold the idea that microorganisms could arise spontaneously. -
Lazzaro Spallanzani
Lazzaro Spallanzani tested spontaneous generation by boiling nutrient-rich broth to kill all microorganisms and then sealing some flasks while leaving others open. The sealed flasks remained free of microorganisms, while the open ones showed microbial growth. When the seals were broken, microorganisms appeared in the previously sterile flasks, proving contamination came from the air. Spallanzani concluded that life does not arise spontaneously. -
Louis Pasteur
In 1861, Louis Pasteur disproved spontaneous generation with his swan-neck flask experiment. He boiled broth in flasks with curved necks that allowed air in but trapped microorganisms. The broth stayed sterile until the flasks were tilted, mixing trapped particles with the broth, which then grew microorganisms. This finally disproved spontaneous generation.