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The idea of non-living objects can give rise to simple living organisms arise among scientists, soon becoming a “common knowledge”.
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1668, Francesco Redi (Italian physician and poet) ----believe maggots developed from eggs laid by flies by conducting an experiment using a variety of flasks with rotten meat inside, some expose the opening to the air, some sealed, some covered. After a few days, he found out that the maggots only appeared in the open flasks, where the flies can lay their eggs.
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In 1745, John Needham (English clergyman) -------believe in spontaneous generation and he created an experiment to prove it: boiling chicken broth and test whether or not microorganisms appeared spontaneously after boiling. After boiling the broth, hesealed it and waited for growth of microorganisms, and it did grow in a few ways, claiming victory for spontaneous generation.
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In 1756-1767, Lazzaro Spallanzani (Italian priest)------did not believe in spontaneous generation. He modified Needham's experiment but creating vacuum space in the flask and no microorganisms grew. However the believers of spontaneous generation argued that Spallanzani had only proven that spontaneous generation could not occur without air.
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1859, Louis Pasteur (French chemist) ------Question the concept of Spontaneous generation, so he conducted the same experiment with Needham and Spallanzani, boiling the broth in a flask, however, he bent the neck of the flask into a S shape, allowing the air in but not the microorganisms.
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As expected, no organisms grew in the broth, but as soon as the broth reached the lowest point of the neck, microorganisms grew rapidly. This experiment proved Needham and Spallanzani’s experiment faulty, putting an end to the theory of Spontaneous generation.
