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400 BCE
Aristotle
He was the first to propose and advocate for the concept of spontaneous generation. -
Jean Baptiste Van Helmont
He was a strong proponent of the theory of spontaneous generation and even devised a method for supposedly "creating" mice using dirty rags and grains. This demonstration significantly contributed to the widespread acceptance of the theory at the time. -
Francesco Redi
An Italian poet and physician named Francesco Redi challenged the theory of spontaneous generation by conducting a simple yet groundbreaking experiment. Redi hypothesized that maggots arose from eggs laid by flies, not from the meat itself. To test this, he placed meat in several jars, sealing some while leaving others open. As predicted, maggots appeared only in the jars that were left open. This demonstrated that maggots were the offspring of flies and not the result of spontaneous generation. -
Anton Van Leeuwenhoek
He discovered bacteria and used his findings to demonstrate how cells and bacteria reproduce and generate from pre-existing life forms, rather than arising spontaneously from non-living matter. -
John Needham
John Needham conducted an experiment to support the theory of spontaneous generation. He boiled chicken broth, placed it in a sealed jar, and observed that microorganisms still grew inside. This result was taken as evidence that life could arise spontaneously from non-living matter, further convincing many people of the validity of the theory at the time. -
Lazzaro Spallanzani
The same year as Needham’s experiment, Italian clergyman Lazzaro Spallanzani challenged his findings. Spallanzani vacuumed the air from the flask, sealed it, and boiled the broth. No microorganisms grew, leading him to dispute spontaneous generation. However, supporters argued that air was necessary for the theory to work. -
Rudolf Virchow
Virchow discovered that cells arise only from pre-existing cells, which further discredited the theory of spontaneous generation. He demonstrated that living things cannot come from non-living matter, as non-living things lack cells. -
Louis Pasteur
French chemist Louis Pasteur definitively disproved the theory of spontaneous generation with an innovative experiment. He boiled meat broth in a flask and bent its neck into an S-shape after heating it. This design allowed air to enter but trapped airborne microorganisms in the curved neck. As no microorganisms grew in the broth, Pasteur not only debunked spontaneous generation but also demonstrated that microorganisms are ubiquitous in the environment. -
Thomas H. Huxley
Thomas H. Huxley gave his "Biogenesis and Abiogenesis" lecture, which provided strong support for Pasteur's work in disproving spontaneous generation. Huxley’s lecture emphasized the principle of biogenesis, the idea that life arises only from pre-existing life, reinforcing the conclusion that spontaneous generation does not occur. His arguments further solidified the rejection of spontaneous generation in scientific thought.