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Aristotle's Age (300 BC)
During the Aristotle's time, spontaneous generation was widely accepted by scientists. Aristotle himself believed in spontaneous generation. In that period of time, it was plausible that living beings could appear from non-living beings (mud, soil, etc.) -
William Harvey and Etymology
For centuries, spontaneous generation remained an accepted fact. However, in the 1600s, Harvey's interest in etymology led him to denouncing spontaneous generation as he believed that maggots and worms originated from eggs. -
Jan Baptist von Helmont and Mice
In the 1600s, Hemont, an advocate for spontaneous generation, conducted many experiments that supported the theory of spontaneous generation. One of his known experiments was his recipe for creating mice. Hemont believed that after leaving soiled clothes and wheat in an open jar and waiting for 21 days would create an adult mouse. -
The Microscope
In the 1600s, a new microscope, one that could see bacteria and things that were once invisible to the naked eye, was created. Scientists discovered that these organisms did not appear spontaneously, so they concluded that spontaneous generation did not occur from visible organisms, but from microorganisms. -
Francesco Redi and Raw Meat
In 1668, Francesco Redi performed an experiment with raw meat. He found that, contrary to what Aristotle thought, raw meat did not spontaneously produce maggots. He found that the maggots that appeared on raw meat were actually from eggs laid by adult flies. -
Lazzoro Spallanzani and His Broth Experiment
In the late 1700s, Spallanzani attempted to disprove John Needham's theory. He suggested that if the flask was sealed after boiling, microorganisms would not develop as the seal would block any out. His experiment was a success, but other scientists simply dismissed it by adapting their theory, stating that Spallanzani only proved that spontaneous generation needed air to occur. -
John Needham and Broth
In 1745, John Needham, an advocate for spontaneous generation, carried out an experiment that would strengthen belief for spontaneous generation. The results of his experiment convinced him that microorganisms could emerge from boiled broth, therefore strengthening his conviction. -
Louis Pasteur and the Swan Neck Flask
Louis Pasteur settled the continous debate of spontaneous generation through his experiment. The swan neck flask allowed air in but the sterile container pushed out bacteria. With the swan neck flask intact, no bacteria grew within the contents despite being in contact with air. However once the neck was broken, microorganisms grew within the previously clear broth. The results disproved the spontaneous generation theory. -
Official Disaprovement of Spontaneous Generation
In 1864, Louis Pasteur's theory was accepted by the France's Academy of Science.
