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Francesco Redi
Francesco Redi born in Arezzo, Italy, 1626-1697, was an Italian physician and biologist who is known for his pioneering work in refuting the theory of spontaneous generation and in showing that living organisms can only arise from other living organisms. -
Redi’s experiment
To test this idea, Redi conducted an experiment in which he placed pieces of meat in four different jars: two of them open and two closed with a lid. He observed that the flies appeared in the open jars, but not in the closed ones. Furthermore, he observed that the flies only appeared on the surface of the meat, suggesting that the larvae did not arise spontaneously from the meat, but were deposited by the flies. -
John Needham
John Needham born September 10, 1713 in London, England and died in 1781, was an English naturalist, microscopist, and Catholic priest who conducted important research in the field of biology. He is known for his experiments that supposedly supported the theory of spontaneous generation. -
Lazzaro Spallanzani
Lazzaro Spallanzani born in the Italian city of Scandiano, in 1729 until 1799, was an Italian naturalist and biologist known for his contributions to the study of animal reproduction and digestion, as well as for his experiments that disproved the theory of spontaneous generation.
Spallanzani was interested in science from an early age and studied at various Italian universities. -
Needham’s rebuttal
Needham's experiment involves briefly heating broth to its boiling point, to kill microorganisms, and pouring it into flasks. Shortly after the broth cooled, she sealed them.
After some time, he observed living microorganisms in the sealed broth, thus he concluded that spontaneous generation was a fact and contradicted Redi's conclusions. -
Criticism from Spallanzani
However, Spallanzani disagreed with Needham's conclusions and conducted hundreds of carefully executed experiments using hot broth.
Spallanzani poured broth into flasks and sealed them. He then boiled the flasks for a long time to kill any microorganisms present.
After a while, the broth had no trace of life. However, once he opened the flask, the microorganisms grew rapidly in the broth.
Spallanzani concluded that spontaneous generation was false and that the microbes came from polluted air. -
Louis Pasteur
Louis Pasteur (1822-1895) was a French microbiologist and chemist who is known for his discoveries in the fields of microbiology and immunology. He is widely regarded as one of the most important figures in the history of science. -
Pasteur puts spontaneous generation to rest
Pasteur for his experiment used containers in which he placed broth, boiled before, for a few minutes. After a rat was removed from the fire and the 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.