Dissolution of the Theory of Spontaneous Generation

Spontaneous generation is the belief that some life forms are created from non-living things. It was an accepted theory to explain the creation of living things since the times of the ancient Romans to the early nineteenth century, when people began to become more skeptical of this idea. By the 20th century, spontaneous generation was known to be an incorrect theory. The reason it was known to be incorrect, primarily, was because of four scientists: Francesco Redi, John Needham, Lazzaro Spallanzani, and Louis Pasteur.

Francesco Redi, in 1668, started the chain of experiments that would all add up to dissolve the theory of spontaneous generation. Redi was able to do this by doing a famous experiment involving meat and flies. He covered a jar of meat so no flies could enter it and, after a few days, there were no flies. This experiment showed that flies were not created from meat. This, in turn, showed to other scientists that "larger" organisms were not created spontaneously. Redi's experiment was monumental because it was the first time spontaneous generation had been disproved by concrete evidence. Along with that, the experiment's result was a step for other scientists to build on in the future. Without Redi's findings, the process of proving spontaneous generation was a false theory could have been delayed drastically.

The next two scientists to make significant impacts on the theory of spontaneous generation were John Needham and Lazzaro Spallanzani.

John Needham was a Scottish clergyman who, from 1745 to 1748, attempted to show that there was a life force in the molecules of all inorganic matter that caused spontaneous generation to occur. He went about doing by doing experiments which showed bacteria would form in soups.

Seventeen years later, Italian biologist Lazzaro Spallanzani tried to disprove Needham's belief. Spallanzani went about this by doing three experiments. The first experiment was done by boiling soup for an hour, putting it in a flask, and then sealing off the flask. The second experiment involved boiling soup for a few minutes, putting it in a flask, and sealing it of. The third experiment was done by boiling soup for an hour, putting it in a flask, and sealing the flask with a cork that let air in. Out of the three experiments, the first experiment was the only one which led to no bacteria forming. From these experiments, Spallanzani figured that an hour of boiling could kill the bacteria and bacteria came to substances through the air.

The result of Spallanzani's experiments was a debate between him and Needham over the process of boiling