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Francesco Redi
Francesco Redi (February 18, 1626, Arezzo, Pisa, March 1, 1697) was an Italian physician, naturalist, physiologist, and writer. He demonstrated that insects are not born by spontaneous generation, he carried out studies on the venom of vipers, and wrote Observations around vipers, 1664. -
Redi’s experiment
Francesco Redi's experiment was performed in 1668 to refute the theory of spontaneous generation. He placed pieces of meat in four different jars. Three of the jars were open, while the fourth was sealed. Redi observed that the flies laid their eggs only on meat that was exposed to air, and maggots only appeared on meat that was exposed to flies. Therefore, Redi concluded that maggots did not arise spontaneously from decaying meat, but rather were the result of the life cycle of flies. -
John Needham
John Needham (1713-1781) was an English naturalist and microscopist known for his studies of microorganisms. In 1745, he carried out an experiment in which he attempted to prove the theory of spontaneous generation, which postulated that certain organisms could arise spontaneously from non-living matter. -
Lazzaro Spallanzani
Lazzaro Spallanzani (1729-1799) was an Italian biologist known for his studies in physiology, anatomy, and microbiology. He is especially known for his experiments on spontaneous generation, in which he challenged the theory that certain organisms could arise spontaneously from non-living matter. -
Needham’s rebuttal
In 1745, John Needham conducted an experiment, boiling meat broth to destroy pre-existing organisms and placing it in a container that was not properly sealed, since according to his theory, air was needed for this to take place.He observed colonies in the container, which did not contradict the theory of spontaneous generation. But Needham argued that air was essential for life, including the spontaneous generation of microorganisms. -
Criticism from Spallanzani
Spallanzani conducted an experiment in which he boiled a nutrient broth in a flask and immediately sealed it to prevent the entry of air. By sealing the flask, he created a sterile environment inside and allowed it to settle, the broth remaining free of microorganisms. He repeated the experiment by allowing air to enter before sealing it, and showed that microorganisms appeared in the broth. -
Louis Pasteur
Louis Pasteur (1822-1895) was a French chemist and microbiologist, considered one of the founders of modern microbiology. He made numerous discoveries and experiments that significantly contributed to our understanding of fundamental biological and chemical processes. -
Pasteur puts spontaneous generation to rest
Pasteur used containers with long, curved necks, in which he placed a broth that had boiled for a few minutes. When it was removed from the heat, air entered through the neck, but the microbes remained trapped in it, which prevented them from contaminating the liquid and allowed it to be kept sterile indefinitely.