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The timeline shows how the theory of spontaneous generation, accepted for centuries, was gradually refuted by key experiments by scientists such as Redi, Spallanzani and Pasteur. This process cemented the principle that life only comes from life, transforming science and microbiology.
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It was discovered that the idea that simple life forms arise spontaneously from nonliving matter is widely accepted. Example: recipes for the spontaneous generation of animals such as scorpions. -
Redi conducts an experiment with meat in open jars covered with gauze. He concludes that maggots do not arise spontaneously, but come from eggs laid by flies.
Impact: First major refutation against spontaneous generation, although it is not yet fully accepted. -
Needham boiled broth and sealed it in jars, observing microorganisms after a while. He concluded that these arose spontaneously. There was also a problem: the experiment had insufficient heating and poor sealing techniques. -
Spallanzani boiled broth in sealed jars for a longer time, avoiding the presence of microorganisms. He concluded that these came from contaminated air, not from spontaneous generation.
Critics' Response They argue that the "vital principle" of the air was eliminated by sealing the jars. -
Pasteur uses swan-neck flasks that allow airflow but prevent the entry of contaminating particles. He boils broth in these flasks and finds no microorganisms until he breaks the neck or tilts the flask.
In conclusion He definitively refutes the theory of spontaneous generation. He establishes that "life comes from life" (Omne vivum ex vivo).