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100
Aristotle's "The History of Animals"
Aristotle explains in his book "The History of Animals," that living organisms either came from parent animals or grew from non-living materials because it contained "vital heat." (This date is actually around 300 BCE, but Timetoast won't let me make points earlier than 100 AD) -
Period: 100 to
Time span of Spontaneous Generation
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First Microscope is Invented
The microscope allowed scientists to continue to believe in spontaneous generation, as they found that by looking at a piece of hay in water under a microscope, organisms would grow, thus supporting the life from non-life theory. -
Francesco Redi Challenges Spontaneous Generation
Francesco Redi, an Italian physician and biologist, contested the idea of spontaneous generation by placing meat in uncovered containers, cloth covered and corked containers. He found that maggots grew upon the uncovered meat, and on the cloth, but that no maggots grew upon the covered meat. He used this to support the idea that organisms grew from parent organisms. -
Needham Boils Broth
John Needham boiled broth and then sealed it. He noticed that even though it was sealed, the broth would still grow cloudy, thus showing that spontaneous generation existed. However, we now know that Needham had not heated the broth for long enough to kill all possible microbes in it. -
Spallanzani's Experiment
Lazzaro Spallanzani, an Italian priest, tried to refute Needham's experiment by recreating the same boiled broth, drawing out some air to make a partial vacuum and then sealing the container instantly. No bacteria growth happened, but supporters of the theory said he simply proved that spontaneous growth could not happen without air. -
Louis Pasteur Disproves Spontaneous Generation
Louis Pasteur recreated Needham's experiments, but with a flask with a long neck that curved downwards. This was to prevent any particles from entering the broth. He found that the broth did not have bacteria growth, thus proving that there was in fact nothing in the air that caused spontaneous generation, disproving the theory. When he broke the neck so particles could fall in, he found that there was bacterial growth, further proving that it was due to particles and not air.
