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Francesco Redi
Francesco Redi was an Italian physician and poet. He is known for being the first to question the theory of Spontaneous generation by performing an experiment that would revolutionize the thinking of that time. The greatest discovery he made was to encourage other scientists to question things. -
Redi's Experiment
Francesco Redi placed pieces of meat in three jars: one open, one sealed, and one covered with gauze. Flies laid eggs only in the open jar, where maggots appeared. This demonstrated that maggots come from fly eggs, not from the meat itself, challenging the idea of spontaneous generation. -
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John Needham
John Needham, a microscopist, was a staunch supporter of the aforementioned theory of spontaneous generation, which was the idea that living organisms can develop from non-living matter. Needham's most important experiment claimed that microorganisms in broth developed independently of other cells. -
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Lazzaro spallanzani
Lazzaro Spallanzani was an Italian biologist and academic responsible for several important discoveries. He is mainly known for his studies on spontaneous generation, a theory that he was able to refute thanks to precise experiments. -
Spallanzani's Experiment
Lazzaro Spallanzani boiled broth for a longer time than John Needham and sealed the containers tightly. No microorganisms appeared in the broth, suggesting that they came from outside contamination, not spontaneously generated. This experiment challenged the idea of spontaneous generation. -
Criticism from Spallanzani
In the same year as his experiment (1765), Lazzaro Spallanzani criticized John Needham's method. He argued that Needham's experiment was flawed because it did not completely seal the containers, allowing air and microorganisms to contaminate the broth. Spallanzani believed that life did not arise spontaneously but from pre-existing life. -
Needham’s Rebuttal
John Needham responded to Spallanzani's criticism in 1767. He argued that Spallanzani's longer boiling process and tightly sealed containers might have destroyed the "vital force" necessary for life to form. Needham believed that this vital force was essential for spontaneous generation, and that Spallanzani’s experiment didn’t allow life to occur naturally. -
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Louis Pasteur
Louis Pasteur is the most globally recognized French scientist. His groundbreaking discoveries in molecular chirality and advancements in fermentation greatly benefited brewers and winemakers. Pasteur introduced the process of pasteurization to sterilize wines and significantly contributed to the development of germ theory, which made Joseph Lister's antiseptic surgical techniques possible. -
Pasteur's Experiment
Louis Pasteur used swan-neck flasks with sterilized broth. The flasks allowed air in but trapped dust and microorganisms in the neck. No life appeared in the broth unless the flask was tipped, proving that microorganisms came from the environment and not from spontaneous generation. This experiment helped disprove the idea of spontaneous generation.