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The Theory of Spontaneous Generation of Organisms

In this the theory of spontaneous generation of organisms post we have briefly explained about of spontaneous generation of organisms, different experiments conducted in 17 century.

The previously popular belief that a living thing could arise or develop from a non-living thing is referred to as spontaneous generation. According to the theory of spontaneous generation, complex, living organisms can be created from non-living matter.

The Theory of Spontaneous Generation of Organisms

Aristotle (384–322 BC), a Greek philosopher, was one of the first to explain the theory of spontaneous generation of organisms, the idea that life might emerge from non-living elements.

According to Aristotle, life can arise from non-living matter if it has pneuma (“vital heat”). As proof, he cited various instances of creatures appearing in previously barren settings, such as the seemingly unexpected arrival of fish in a new pool of water.

17th Century Experiments

This the theory of spontaneous generation of organisms lasted until the seventeenth century, when scientists conducted more theory of spontaneous generation of organisms experiment to establish or reject it. Frogs simply arise along the muddy banks of the Nile River in Egypt during the annual floods, according to the the theory of spontaneous generation of organisms proponents.

Mice just arrived among grain stored in barns with thatched roofs, according to some. Mice appeared when the ceiling leaked and the grain moulded. Mice could be created from rags and wheat kernels left in an uncovered container for three weeks, according to Jan Baptista van Helmont, a seventeenth-century Flemish scientist. In truth, such environments provided optimal food and shelter for mouse populations.

Francesco Redi (1626–1697)

However, one of van Helmont’s contemporaries, Italian physician Francesco Redi (1626–1697), conducted an experiment in 1668 to prove the theory of spontaneous generation of organisms that was one of the first to refute the idea that maggots (fly larvae) generate spontaneously on meat left out in the open air.

He predicted that preventing flies from coming into direct contact with the meat would also prevent maggots from appearing. Redi had placed meat in each of the six containers. Two were open to the elements, two were gauze-wrapped, and two were tightly sealed.

His hypothesis was supported when maggots appeared in the uncovered jars but not in the gauze-covered or tightly sealed jars. He came to the conclusion that maggots could only form when flies were allowed to lay eggs in the meat, and that the maggots were the offspring of flies rather than the result of spontaneous generation.

Spontaneous Generation Theory

The Theory of Spontaneous Generation of Organisms Figure: Francesco Redi’s theory of spontaneous generation of organisms experiment setup consisted of an open container, a container sealed with a cork top, and a container covered in mesh that let in air but not flies. Maggots only appeared on the meat in the open container. However, maggots were also found on the gauze of the gauze-covered container. 

John Needham (1713–1781)

John Needham (1713–1781) published a report on his own experiments in 1745 about the theory of spontaneous generation of organisms in which he briefly boiled broth infused with plant or animal matter in the hopes of killing all pre-existing microbes. The flasks were then sealed.

Needham noticed that the broth had become cloudy after a few days and that a single drop contained numerous microscopic creatures.

He contended that the new microbes had to have emerged spontaneously. In reality, he most likely did not boil the broth long enough to kill all of the preexisting microbes.

Lazzaro Spallanzani (1729–1799)

Lazzaro Spallanzani (1729–1799), on the other hand, disagreed with Needham’s conclusions and conducted hundreds of meticulously executed theory of spontaneous generation of organisms experiment with heated broth.

As in Needham’s the theory of spontaneous generation of organisms experiment, broth was infused with plant and animal matter in both sealed and unsealed jars. Needham’s findings were contradicted by Spallanzani’s findings: Unless the flasks were opened to the air, heated but sealed flasks remained clear, with no signs of spontaneous growth. This suggested that microbes were introduced from the air into these flasks.

Needham responded to Spallanzani’s findings by claiming that life is derived from a “life force” that was destroyed during Spallanzani’s extended boiling.

Any subsequent sealing of the flasks prevented new life force from entering and resulting in spontaneous generation.

Further Readings

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