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Francesco Redi's
Redi's experiment showed that maggots in rotting meat came from fly eggs, not from the meat itself. That he did it taking a pot with meat and covering it in different ways, the one that helped to affirm his hypothesis was when he covered it with a gauze to avoid that the flies put eggs in it, but if they put them outside. -
John Needham's
He wanted to disprove redi's thinking so he created his experiment to verify his hypothesis. The experiment involved boiling chicken broth, so that it would kill all the microorganisms. To make sure that no other factors would be affected, he sealed the flask. Later, he found microorganisms in the broth and concluded that they had arisen spontaneously. -
Lazzaro Spallanzani's
He repeated Needham's experiment, to ensure that they did not arise spontaneously, but instead of sealing the flask, he boiled it to sterilize its contents and then sealed it. Some time later no microorganisms grew in the flask, which led Spallanzani to conclude that they did not arise spontaneously but came from the air. -
Louis Pasteur's Experiment
It consisted of designing a flask with a long, curved neck that allowed air to enter but prevented the entry of dust and microorganisms. He then boiled the broth inside the flask to sterilize it, and no microorganisms grew in the broth. So he was able to provide strong evidence that spontaneous generation did not exist.