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Francesco Redi's experiment
Francesco Redi's experiment consisted in seeing if maggots appeared spontaneously from meat. So he did the same experiment in three pots with different conditions.
In the first condition, where the meat was in open jars with flies around it, maggots appeared.
In the second condition, where the meat was in a tightly sealed jar, maggots didn't appear.
In the last condition, where the meat was covered with a fine mesh, no maggots appeared either. -
Francsco Redi's experiment Part 2
Redi came to the conclusion that the maggots didn't appear spontaneously from the meat, but from fly eggs. He was able to demonstrate that the idea of spontaneous generation was incorrect. -
John Needham's experiment
In his experiment, Needham boiled broth in a covered flask. He believed that the boiling would kill any pre-existing microorganisms in the broth and that the closed flask would prevent any new ones from entering. However, when he later examined the broth, he found microorganisms on it.
Needham's experiment support the theory of spontaneous generation, as microorganisms had arisen spontaneously in the broth. However, his results were called into question by another biologist, Lazzaro Spallanzani. -
Lazzaro Spallanzani's experiment
Lazzaro Spallanzani repeated Needhams experiment to show that they didn't appear spontaneously. He showed that sterilized broth in properly sealed flasks didn't produce microbial growth unless exposed to air, which shows that the microorganisms came from the air rather than appearing spontaneously in the broth.
That prove that the flasks used by John Needham in his experiment were not properly sealed. -
Louis Pasteur's experiment
Louis Pasteur's experiment consisted of placing boiled broth in flasks with long, curved necks that prevented the entry of microorganisms and dust. He boiled the broth to sterilize it and he saw that no microbial grew. The swan-necked flask prevented any microorganisms that were present in the air from entering the sterilized broth, what proves that microorganisms don't arise spontaneously, but come from pre-existing microorganisms.