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Disproval of Spontaneous Generation in Larger Organisms
In 1668 Francesco Reidi conducted an experiment to disprove the idea of spontaneous generation in larger organisms. He tested the idea of flies spontaneously generating from rotting meat by putting the meat in 3 sets of containers, one open, one sealed shut, and one covered in gauze. He observed that the sealed jars produced no signs of flies or maggots, and this made the public accept that larger organisms must have come from parents. -
The Idea of "Life Force" - John Needham
Since microorganisms were a new concept, many didn't understand where these microscopic creatures came from, and it seemed perfectly logical that they could possibly be the result of spontaneous generation. John Needham experimented with spontaneous generation in microorganisms by observing boiled chicken broth. In the jars that were open to air he discovered an abundance of microorganisms, leading him to believe that there was a 'life force' in the air that caused spontaneous generation. -
Lazzaro Spallanzanis Experiments
Lazzaro Spallanzani did a variation of Needhams experiments; boiling soup for an hour and sealing the glass flasks by melting them shut, yeilded sterile soup. He boiled another batch for a few minutes, sealed it, and microorganisms were present. In the third batch, he boiled soup for an hour and sealed it with a cork, letting air in allowing microorganisms to grow. This sparked a debate between Spallanzani and Needham which would eventually lead to the final disproving of spontaneous generation. -
Needham vs. Spallanzani and the Paris Academy of Sciences
The debate between Needham and Spallanzani got so heated that the Paris Academy of Sciences eventually offered a prize to anyone who would settle the debate. Needham, a strong believer in the concept of 'life force', argued that Spallanzanis 'over-extensive boiling' had killed the life force in the containers and the absence of bacteria in the soup was due to the absence of life force in the containers. -
The Downfall of Spontaneous Generation
The prize was eventually claimed by a man named Louis Pastuer who disproved spontaneous generation in microscopic organisms. He did this by boiling broth and putting them in containers exposed to the air, such as open-mouthed flasks. Some of the containers, although exposed to the air, were filtered. These filtered bottles weren't contaminated and the soup inside remained sterile, whereas the open-mouthed flasks produced bacteria. This disproved spontaneous generation for once and for all.