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Francesco Redi
Francesco Redi was an Italian physician and biologist who is best known for his experiments on spontaneous generation, a widely held belief at the time that living organisms could arise from non-living matter. -
Redi's experiment
In his experiment, he used three jars containing rotting meat and demonstrated that the larvae that appeared did not arise from the meat itself, but rather from eggs laid by flies. Redi concluded that spontaneous generation was false, and his work paved the way for the germ theory of diseases. -
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John Needham
John Needham was an English biologist and Roman Catholic priest known for his controversial experiments on spontaneous generation. He claimed that microbes spontaneously generated from boiled broth, which was later disputed by other scientists. -
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Lazzaro Spallanzani
Lazzaro Spallanzani was an Italian biologist and Catholic priest known for his work on reproductive biology and his criticisms of John Needham's experiments on spontaneous generation. He demonstrated that sealed flasks prevented microbial growth. -
Needham’s rebuttal
In an attempt to defend his work on spontaneous generation, John Needham conducted a series of experiments in which he boiled broth and then sealed the flasks. However, he found that microbes still appeared in the broth, which he took as evidence for spontaneous generation. This led to a heated debate with other scientists, including Lazzaro Spallanzani, who argued that the flasks needed to be completely sealed in order to prevent contamination. -
Criticism from Spallanzani
The Spallanzani experiment was a replication of the Needham experiment, but with a few important changes. The Spallanzani experiment used aseptic techniques, by boiling the experimental mixture for a longer period of time than Needham had and by sanitizing the flasks the mixture was held in for the experimental period. Spallanzani's Experiment thereby proved spontaneous generation does not exist.