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Period: Jan 12, 1579 to
Jean-Baptiste van Helmont
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Jean-Baptiste van Helmont's Experiment
Jean-Baptiste van Helmont conducted his famous willow experiment. This experiment was conducted by first weighing the soil in a planter and then a willow seed was added. After the willow was fully grown the soil was weighed again. The soil hadn't lost a significant amount of weight while the tree had gained over a hundred pounds in it's growth. From this it was determined that life came spontaneously from nonliving things, or what he thought was water. He discovered the basics of photosynthesis. -
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Francesco Redi
Francesco Redi is most famous for his excellent demonstration of the use of controlled experiments.In 1668 he published his book called “Esperienze intorno alla generazione degl’insetti” which means “Experiments on the Generation of Insects.” -
Francesco Redi's Experiment (Biogenesis)
In 1668, Francesco Redi, an Italian scientist, tested the abiogenesis theory. He placed fresh meat in each of two different jars. One jar was left open; the other was covered with a cloth. Days later, the open jar contained maggots, whereas the covered jar contained no maggots. He did note that maggots were found on the top of the cloth that covered the jar. From this, it was clear the maggots came from fly eggs and thereby disproving the abiogenesis theory. -
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John Needham
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Lazzaro Spallanzani
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John Needham's Experiment (Abiogenesis)
In England, John Needham conducted an experiment where he placed a broth into a bottle, heated the bottle to kill anything living inside, then sealed it. Days later, he found life in the broth and announced that life had been created from nonlife. Therefore John Needham supported the abiogenesis theory as a result of his experiment where life seemed to have come from nonlife. However, in reality, he did not heat the broth long enough to kill all life. -
Lazzaro Spallanzani's Experiment (Biogenesis)
Spallanzani, also an Italian scientist, reviewed both Redi's and Needham's data and experiments and concluded that perhaps Needham's heating of the bottle did not kill everything inside. He did his own experiment by placing broth in two separate bottles, boiling the broth in both bottles, then sealing one bottle and leaving the other open. Days later, the unsealed bottle contained living things and the sealed bottle contained no signs of life.This also disproved the abiogenesis theory. -
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Louis Pasteur
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Louis Pasteur's Experiment (Biogenesis)
Louis Pasteur, a French scientist, accepted the challenge to re-create Spallanzani's experiment since there was debating about how abiogenesis needed air to work and Spallanzani trapped the air out and therefore not conducting a fair experiment for abiogenesis. Pasteur decided to have an experiment that would leave the system open to air to finally prove that air being eliminated from Spallanzani's experiment was not the reason why no living things were formed. (continuation on next event) -
Continuation of Louis Pasteur's Experiment
He designed bottles with S-curved necks that would prevent access of air materials. He placed broth in one of these bottles, boiled the broth, and observed no life in the jar for one year. He then broke off the top of the bottle, exposing it more directly to the air. He found life-forms in the broth within days. He discovered that those life-forms came from other life-forms in the air. So Pasteur finally proved that even if exposed to air, life did not arise from nonlife.
