Francesco Redi Vs. Spontaneous Generation

Muskaan Taneja, 9SC

Honors Biology – Dr. Speyer

August 20, 2016

Francesco Redi vs. Spontaneous Generation

        Have you ever noticed that if you drop a piece of food on the ground you see ants forming around it? We now know that ants are attracted to the odor of sugar. However, before the 17th century people used to believe that instead of ants hatching from eggs, they are created when food is dropped on the ground. Can nonliving matter produce living organisms? Before studies were involved, everyone thought that this was the case. Other examples of spontaneous generation were that rats were created by waste laying on the street, frogs existed from muddy banks along the riverside, and last but not least rotting meat generated flies. The idea of spontaneous generation first arrived from Aristotle. The term spontaneous generation is the supposed production of living organisms from nonliving matter. Before Francesco Redi everyone believed Aristotle’s false speculation was true. Redi disapproved of Aristotle’s theory, deciding to create a controlled experiment using the scientific process.

“He read in the book on generation by William Harvey a speculation that vermin such as insects, worms, and frogs do not arise spontaneously, as was then commonly believed, but from seeds or eggs too small to be seen.” (Rogers, K. (September 1, 2009). Francesco Redi. Retrieved from https://www.britannica.com/biography/Francesco-Redi)

In 1688, Francesco was the first person to oppose the theory of spontaneous generation by demonstrating that maggots come from eggs of flies. His experiment consisted of series of jars containing meat. Half of them were left open, and half of them were sealed with muslin. He observed them closely for many days and recorded his examinations. After a few days he repeated the experiment with a netted jar so the air could enter. His results were as expected. The meat was decomposed, and the open and netted flasks contained maggots. Then he formed a conclusion stating that living organisms cannot form from nonliving matter.

After publishing his theory, Francesco became one of the most respected scientists. “Redi soon gained a reputation throughout Europe as one of the most reputed biologists after he published “Esperienze intorno alla generazione degl’insetti” in 1668 (English: Experiments on the Generation of Insects). The work still remains highly influential in history for effectively rejecting the widely popular belief of spontaneous generation.” ("Francesco Redi." Famous Scientists. N.p., n.d. Web. 21 Aug. 2016.)  

Redi’s theory was shocking news for everyone. Not everyone believed it was the end of spontaneous generation. John Needham, a scientist from England, tried to prove Redi wrong by conducting another experiment. He placed a broth into a bottle, heated the bottle to kill anything inside, then sealed it. Days later, he concluded the presence of life in the broth and argued that life formed from nonlife. In actuality, he did not heat it long enough to kill all the microorganisms.

Francesco Redi wasn’t the only scientist who did not approve of life arising from the nonliving. Louis Pasteur was a French scientist who generated the germ theory (pathogenic theory of medicine) and the cell theory to get a better understanding of spontaneous generation. In 1859, he conducted an experiment that solved all his confusion. Pasteur applied heat to a flask containing meat broth. The flask was curved so that falling particles could not reach the broth but the air could freely flow through it. Nothing grew in the broth unless the flasks were broken open, proving that the living organisms that grew in such broths came from outside rather than spontaneously generating in the broth. This was one of the last and most vital experiments contradicting the theory of spontaneous generation.