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Francesco Redi's experiment
An Italian poet and physician named Francesco Redi decided to conduct an experiment against the spontaneous generation theory. Redi believed that maggots came from the eggs that were laid by flies so he put meat in various jars and sealed a few and left a few open. As he expected, only the jars that were open to air had maggots in it. This proved his theory because when the jars are sealed, flies were unable to lay eggs on the meat so there were no maggots. -
John Needham
John Needham did an experiment where he boiled meat broth to destroy the pre-existing organisms and placed it in a container that was not properly sealed, since according to his theory, air was needed for this to take place. After some time, he observed colonies in the container, which did not contradict the theory of spontaneous generation. People were more certain about the theory of spontaneous generation. -
Lazzaro Spallazani
In the same year John Needham conducted the chicken broth experiment, an Italian clergyman was not convinced. He modified Needham’s experiment and vacuumed the air out before sealing the chicken broth and boiling it. During that experiment, no microorganisms grew. However, some believers disagreed with Spallanzani and said he simply just proved that the theory needs air to work -
Louis Pasteur
A French chemist Pasteur proved the spontaneous generation theory wrong. He performed a combined experiment of Needham’s and Spallazani’s. He boiled meat in a flask and heated the neck of the flask and bent it to an S shape. This allowed air to go into the flask but does not allow air borne microorganisms because they will settle on the S. Since no microorganisms grew, Pasteur proved the spontaneous generation theory wrong and also demonstrated microorganisms are everywhere.
