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Francesco Redi
Francesco Redi was an Italian doctor, naturalist, physiologist and a lawyer. At that time, it was widely held that maggots arose spontaneously in rotting meat. To achieve his goal of proving spontaneous generation to be wrong, he did a very important experiment. His hypothesis was: “If we cover the cup with a cap/cloth, then flies can’t lay eggs, because they can’t enter. This became to be true, and proved that spontaneous generation was an incorrect hypothesis. -
Redi's Experiment
- In the first cup, he didn't put any cover. As a result, the flies laid eggs and maggots grew on the meat.
- In the second one, he covered the cup with meat with a cover. As a result, the flies didn't laid eggs and any maggot grew on the meat.
- Finally, he covered the third cup with a cloth. As a result, the flies were attracted by the smell of meat, but since they couldn't get in, they laid eggs in the cloth. Redi proved that spontaneous generation was impossible in macroorganisms.
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John Needham
John Turberville Needham was an English biologist and Catholic priest. As Redi had experimented with macroorganisms, the hypothesis that spontaneous generation only occurred with microorganisms made Needham do a new experiment. -
Needham's experiment
Needham's experiment consisted of briefly boiling a broth mixture and then cooling the mixture in an open container. Later, the flasks would be sealed, and microbes would grow a few days later. Because of this result, John thought that spontaneous generation was possible. -
Lazzaro Spallanzani
Lazzaro Spallanzani was a naturalist and Catholic priest that was in a disagreement with Needham's conclusions. Spallanzani concluded that spontaneous generation was false and microorganisms came from contaminated air. -
Spallanzani's experiment
Spallanzani poured broth into flasks and sealed them. Next, he boiled the flasks for a long time, to kill present microorganisms.
After some time, the broth did not have any trace of life. However, once he unsealed the flask, the microorganisms rapidly grew in the broth. -
Pasteur's experiment
He designed several bottles with S-curved necks so the microorganisms couldn't arrive to the booth, but the air could circulate. After a year, he didn't observe any living organism. Then, he exposed it more directly to the air and trapped particles, and noted life forms in the broth. -
Louis Pasteur
Louis Pasteur, a notable French scientist, re-created the experiment and leave the system open to air.
He demostrated an reasoned that the contamination came from life forms in the air, not spontaneously.