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Francesco Redi (1626-1697)
Francesco Redi was an Italian physician, biologist, and poet who is best known for his experiments on the spontaneous generation of life. He is credited with being one of the first scientists to challenge the prevailing belief that life could arise spontaneously from non-living matter. Redi conducted a series of experiments against spontaneous generation. -
Redi’s experiment
Francesco Redi conducted an experiment to disprove spontaneous generation by showing that maggots only appeared on meat that was exposed to flies. From this observation, Redi concluded that the maggots did not spontaneously generate from the meat, but rather were the result of eggs laid by flies. This experiment helped to disprove the theory of spontaneous generation and simplified the way for the development of modern germ theory. -
John Needham (1713-1781)
John Needham was an English naturalist and Catholic priest who is known for his controversial experiments on spontaneous generation. Needham believed that microbes could arise spontaneously from non-living matter and conducted experiments in which he boiled broth and then sealed it in a flask. Despite his efforts to sterilize the broth, he found that microbes still appeared in the flask, which he believed supported his theory of spontaneous generation. -
Lazzaro Spallanzani (1729-1799)
Lazzaro Spallanzani was an Italian Catholic priest, biologist, and physiologist who is known for his experiments on digestion, respiration, and reproduction. Spallanzani conducted a series of experiments that challenged the theory of spontaneous generation. He demonstrated that when broth was boiled and then sealed in a flask, no microbes would appear unless the flask was opened to the air, which he concluded was evidence that microbes came from the air and not from the broth itself. -
Needham’s rebuttal
John Needham conducted an experiment where he heated broth to kill any microorganisms and then sealed the flasks. However, microorganisms still appeared in the broth, leading Needham to conclude that spontaneous generation had occurred, leading Needham to conclude that spontaneous generation had occurred Needham's rebuttal helped to clarify the historical understanding of the development of scientific knowledge in China and the West. -
Criticism from Spallanzani
Lazzaro Spallanzani repeated Needham’s experiment but heated the broth for a longer time and sealed the flasks more tightly. No microorganisms appeared in the broth, leading Spallanzani to conclude that spontaneous generation did not occur. This was an important contribution to the understanding of biology and helped pave the way for the development of the germ theory of disease, which holds that many diseases are caused by microorganisms. -
Louis Pasteur (1822-1895)
Louis Pasteur was a French microbiologist and chemist who is known for his discoveries in the field of microbiology, including the germ theory of disease and the process of pasteurization. Pasteur conducted a series of experiments that built on the work of Spallanzani and other scientists to show that microorganisms were responsible for fermentation, and that they could be killed by heating. -
Pasteur puts spontaneous generation to rest
Louis Pasteur demonstrated the non-existence of spontaneous generation by recreating Spallanzani’s experiment but leaving room for air to enter the broth. The broth remained free of microorganisms as long as the neck of the flask remained intact and unopened. However, when the neck of the flask was broken, microorganisms started to appear in the broth. This discovery had a significant impact on the understanding of biology and helped to establish the field of microbiology.
