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4 BCE
Aristotle's Time
At Aristotle's time in 4 century B.C, it was believed by the people that simple living things could appear from non-living things. Also, it was common "knowledge" that simple organisms like worms, beetles, frogs, and salamanders could come from dust and/or mud. One observation was that when rainwater leaked through the roof to the grain which was stored in the barn and leading to moldy grain, mice would appear out of nowhere. Deriving to the conclusion that mice came from moldy grain -
Francesco Redi Tries to Disprove Spontaneous Generation
Francesco Redi, an Italian Physician, was set out to test the idea of spontaneous generation. He put meat in flasks and set them out in various locations, some in open air, others completely sealed.If spontaneous generation was possible, maggots would appear in all the flasks. However, maggots only appeared in the flasks which were exposed to air. Although he constructed a well-executed experiment, however belief in spontaneous generation was still strong. -
Birth of the Microscope and Spontaneous Generation
The microscope allowed people to observe smaller microorganisms. These smaller microorganisms were never seen but were associated with things like organisms generating in water with hay. Spontaneous generation was the only explanation for these new discoveries which seemed to come out of nowhere, further enhancing the belief of spontaneous generation. -
John Needham Defense on Spontaneous Generation
In 1745, John Needham, and English Clergyman proposed to justify Spontaneous Generation. With everyone knowing that boiling killed microorganisms, proposing an experiment to prove spontaneous generation. He boiled chicken broth, put it into a flask and then sealed it, and waited. As he expected microorganisms grew and he thought he had proved spontaneous generation to be valid once and for all. -
Lazzaro Spallanzani Disproves John Needham
Lazzaro Spallanzani, an Italian priest, believed that the experiment conducted by John Needham had some errors. He believed that microorganisms entered the broth from the air after it was boiled. He modified the experiment and proved that microorganisms did not grow and that spontaneous generation could not occur without air. -
Louis Pasteur Puts Spontaneous Generation to rest
The young french chemist, Louis Pasteur finally put the spontaneous generation to rest. He conducted an experiment with a variation of Needham and Spallanzani's He boiled meat broth in a flask, heated the neck of the flask in a flame until it became able to modify, and bent it into the shape of an S. So that air could enter but microorganisms could not. When he bent the flask back, microorganisms grew like he expected.
