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Redi’s experiment
Redi's experiment consisted of placing meat in open and closed jars to see if the flies appeared from the meat or from nowhere. Redi found that the flies appeared only on meat exposed to the fly eggs, not on meat that was covered and protected.
Redi showed that the maggots emerging from rotting meat were fly larvae that had settled on the meat after the death of an animal, and had not spontaneously generated from rotting meat. -
Needham’s rebuttal
Needham's experiment was an attempt to refute the theory of spontaneous generation. Needham heated broth in sealed flasks with cork stoppers, but observed that microorganisms appeared in the broth after some time. He concluded that this supported the theory of spontaneous generation, as the heating would have killed any microorganisms present in the original broth. -
Criticism from Spallanzani
Spallanzani's experiment showed that spontaneous generation only occurs when the air entering a jar contains the necessary germs. By boiling and sealing a jar, you keep out these germs. This experiment supported the theory of biogenesis, which holds that all life comes from other pre-existing life, and refuted the theory of spontaneous generation. -
Pasteur puts spontaneous generation to rest
Pasteur's experiment refuted the theory of spontaneous generation by demonstrating that air carried microorganisms into the nutrient broth and that by bending the neck of the flask, the entry of said microorganisms was prevented. It consisted of filling two flasks with nutrient broth and curving the neck of one of them in the shape of an S, observing that the broth in the curved flask remained free of microorganisms while the one in the other flask was full of them after a few days.