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Francesco Redi
Redi conducted an experiment to disprove the idea that maggots could spontaneously arise from any piece of rotting meat. He placed a piece of meat in three jars, leaving one open, one covered with gauze, and one tightly closed. After a few days, the maggots only appeared in the jar that was open, where the flies could lay their eggs in the meat, showing that the maggots did not arise spontaneously. -
John Needham
Needham wanted to carry out an experiment that consisted of heating broth to kill any existing microorganisms and then sealing the flask. However, microorganisms appeared in the broth, and Needham claimed this was evidence of spontaneous generation. However, critics argued that the sealing process was not effective in killing all microorganisms, so they could have contaminated the broth after heating it. -
Lazzaro Spallanzani
Spallanzani repeated Needham's experiment with the only difference that he boiled the broth longer and sealed the flask more effectively. This time no microorganisms appeared in the broth, which may demonstrate that spontaneous generation did not occur. However, critics argued that Spallanzani's experiment was flawed, as the long boiling process may have destroyed any potential life force required for spontaneous generation to occur. -
Louis Pasteur
Pasteur conducted a series of experiments using a curved-necked flask that allowed air to enter but prevented microorganisms from entering. He showed that sterilized broth in the flask remained free of microorganisms unless the neck of the flask was broken, allowing microorganisms to enter. This experiment conclusively disproved spontaneous generation and led to the acceptance of the germ theory of disease.