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Francesco Redi's experiment
The goal of Francesco Redi's experiment was to determine whether flesh would naturally produce maggots. He then repeated the experiment under various settings in three different pots.
Maggots were visible in the first situation, where the meat was in open jars with flies around it.
Maggots didn't show up in the second situation, when the meat was contained in a securely closed jar. No maggots also appeared in the final condition, where the flesh was coated with a fine mesh. -
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(PART 2) - Francsco Redi's experiment
Redi came to the conclusion that fly eggs, rather than naturally occurring maggots in the meat, caused the problem. He was successful in disproving the fallacy of spontaneous genesis. -
John Needham's experiment
Needham heated "water" in a covered flask as part of his experiment. He reasoned that the boiling would eliminate any pre-existingorganisms in the liquid and that the flask's closure would keep out any further ones. He discovered microbes on the liquid, though, when he later studied it.
Given that microorganisms had developed spontaneously in the broth, Needham's experiment supports the hypothesis of spontaneous genesis. However, Lazzaro Spallanzani, a different biologist, disputed his findings. -
Lazzaro Spallanzani's experiment
Needham's experiment was replicated by Lazzaro Spallanzani, an Italian scientific who to demonstrated that they didn't appear on their own. He showed that sterilized soup in well closed flasks did not promote microbial growth unless exposed to air, demonstrating that the organisms began in the air rather than spontaneously coming in the liquid.
This demonstrates that John Needham's experiment used improperly closed flasks. -
Louis Pasteur's experiment
In Louis Pasteur's experiment, some soup was cooked and placed in flasks with long, curved necks to keep out dust and bacteria. He boiled the soup to kill any bacteria, and he observed that nothing grew. The swan-necked flask proved that microbes do not develop spontaneously, but rather emerge from pre-existing bacteria by preventing any "air" microorganism from entering the sterilized soup.