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Francesco Redi
Redi was mainly knwon because if the way he showed that insects are not born by spontaneous generation, which meant to Francesco the honor of being considered the founder of helminthology. In 1684, he set out the results of his experiments in a treatise. -
Redi's Meat Experiment
At that time, it was thought that maggots generated spontaneously in rotting meat. To prove this as wrong, he made a controlled experiment where flies had to manage to arrive to a piece of meat inside a container. The independent variable was the meat and the variable one was the way the recipient was sealed. -
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John Needham
He was an English naturalist and Roman Catholic cleric. He is mostly known because of his theory of spontaneous generation and the scientific evidence he had presented to support it. -
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Lazzaro Spallanzani
Spallanzani is considered as the main scientist of artificial insemination, as well as for his also very famous refutation of the theory of spontaneous generation with an experiment that would later be resumed and perfected by Louis Pasteur. -
Needham's Broth Experiment
Microscopy exposed microorganisms that appeared spontaneously. Some scientists thought that while spontaneous generation might not apply to larger organisms like maggots and flies, it might still be applicable to smaller microbes. So, Needham heated broth to its boiling point to kill microorganisms, and poured it into flasks. After the broth cooled, he sealed them. He observed living microorganisms in the sealed broth, contradicting Redi’s conclusions. -
Spallanzani's Broth Experiment
To refute Needham's theory, Spallanzani put broth into flasks and sealed them. And then, boiled the flasks to kill the microorganisms in it. After some time, the broth didn't contain life. However, when he unsealed the flask, microorganisms rapidly grew in the broth.
Spallanzani concluded that spontaneous generation was false and microbes came from contaminated air. -
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Louis Pasteur
French chemist and bacteriologist, is considered as the founder of microbiology and the main pioneer of modern medicine. -
Pasteur's S-Curved Bottles Experiment
Louis Pasteur tried to repeat the broths experiments, so he designed bottles with S-curved necks oriented downward. Louis placed a nutrient-enriched broth in one of the bottles, boiled the broth, and observed no life in the recipient for one year. Then, he broke the top of the bottle, exposing it more directly to the air, and noted life forms in the broth in a few days. So, his conclusion was that the contamination came from life forms in the air.