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Francesco Redi
Francesco Redi, a 17th-century Italian physician and biologist, conducted experiments that challenged the theory of spontaneous generation. He also made significant contributions to medicine and biology, writing several books on topics such as poisons and parasites, and was recognized for his expertise in these areas. -
Redi’s experiment
This experiment sought to deny the theory of spontaneous generation. It consisted of putting pieces of meat in three containers, one covered with a fine mesh, another with a thick mesh, and one uncovered.
The uncovered jar was the only one that presented worms, so Redi concluded that the worms were not generated spontaneously, but rather came from the eggs of the flies. -
John Needham
John Needham was an English naturalist and theologian of the 18th century. He conducted experiments that supported the theory of spontaneous generation, which was later disproven by Lazzaro Spallanzani. -
Lazzaro Spallanzani
Lazzaro Spallanzani was an influential Italian biologist and physiologist of the 18th century. He is known for discovering the process of fertilization and for his rigorous experiments that helped to disprove the theory of spontaneous generation. Spallanzani also made significant contributions to the study of digestion, limb regeneration, and echolocation. Today, Spallanzani is celebrated for his important contributions to the development of modern science. -
Needham’s rebuttal
To support the theory of spontaneous generation, Needham briefly heated the broth to its boiling point to kill the microorganisms and poured it into flasks. Shortly after the broth had cooled, he sealed them.
After some time, he observed live microorganisms in the sealed broth, thus concluding that spontaneous generation was a fact. -
Criticism from Spallanzani
Lazzaro Spallanzani (1729–1799) didn't agree with Needham’s conclusions. So he 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, microorganisms rapidly grew in the broth.
Spallanzani concluded that spontaneous generation was false and microbes came from contaminated air. -
Pasteur puts spontaneous generation to rest
Louis Pasteur's experiments in the 1860s proved that spontaneous generation of life is not possible. He demonstrated that sterilized broth in a closed container remained sterile, while broth exposed to air contained microorganisms. This helped establish the germ theory of disease.