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Francesco Redi (1668)
Experiment: Redi placed raw meat in three jars:
Open to the air.
Covered with a fine mesh.
Sealed completely.
Results: Maggots appeared only in the open jar, where flies could lay eggs.
Conclusion: Maggots come from flies, not meat, proving that life does not arise spontaneously.
Schematic:
Open jar → Maggots.
Mesh jar → No maggots, flies on mesh.
Sealed jar → No maggots. -
John Needham (1745)
Experiment: Needham boiled broth, sealed it in flasks, and observed microorganisms growing.
Claim: Supported spontaneous generation, believing boiling killed all life, and new life arose from the broth. -
Lazzaro Spallanzani (1768)
Experiment: Spallanzani boiled broth for longer and sealed the flasks more tightly. No microorganisms grew unless the seal was broken.
Results: Microorganisms came from the air, not spontaneously from the broth.
Schematic:
Open flask → Growth of microorganisms.
Sealed flask → No growth. -
Louis Pasteur (1861)
Experiment: Pasteur used swan-neck flasks filled with boiled broth. The flask’s shape allowed air in but trapped dust and microorganisms.
Results: No microbial growth in the broth until the flask was tilted or broken, allowing particles to enter.
Conclusion: Life comes from existing life (biogenesis).
Schematic:
Swan-neck flask → No growth.
Broken flask → Growth.