Francesco Redi

For more information on Francesco Redi, visit Britannica.com.

Italian biologist, physician, and poet (1626–1697)

Redi, who was born at Arezzo in Italy, studied medicine and philosophy at the University of Pisa, graduating in 1647. He was employed as personal physician to Ferdinand II and Cosimo III, both grand dukes of Tuscany. Intellectually, Redi displayed a variety of talents, being a noted poet, linguist, literary scholar, and student of dialect. On the scientific side, he laid the foundations of helminthology (the study of parasitic worms) and also investigated insect reproduction.

As a biologist he is best known for his experiments to test the theory of spontaneous generation. These were planned to explore the idea, put forward by William Harvey, that flies and similar vermin do not arise spontaneously but develop from eggs too small to be seen. Redi prepared eight flasks of various meats, with half left open to the air and half sealed. Maggots were found only in the unsealed flasks where flies had been able to enter and lay their eggs. That this effect was not due to the presence or absence of fresh air was shown by a second experiment in which half the flasks were covered with fine gauze. Again, no maggots developed in these. This was one of the earliest examples of a biological experiment planned with proper controls. Redi still believed, however, that spontaneous generation occurred in such animals as intestinal worms and gall flies, and it was not until the time of Louis Pasteur that the spontaneous-generation theory was finally discredited.

Redi is featured in many modern-day science textbooks due to his experiment.

Francesco Redi (Arezzo, February 18, 1626 – Pisa, March 1, 1697) was an Italian physician.

He is most well-known for his series of experiments, published in 1668 as Esperienze Intorno alla Generazione degl'Insetti (Experiments on the Generation of Insects) which is regarded as one of the first steps in refuting "spontaneous generation" - a theory also known as Aristotelian abiogenesis. At the time, prevailing wisdom was that maggots formed naturally from rotting meat.

In the experiment, Redi took six jars, which he divided in two groups of three: in the first jar of each group, he put an unknown object; in the second, a dead fish; in the last, a raw chunk of veal. Redi took the first group of three, and covered the tops with fine gauze so that only air could get into it. He left the other group of jars open. After several days, he saw maggots appear on the objects in the open jars, on which flies had been able to land, but not in the gauze-covered jars.

He continued his experiments by capturing the maggots and waiting for them to metamorphose, which they did, becoming flies. Also, when dead flies or maggots were put in sealed jars with dead animals or veal, no maggots appeared, but when the same thing was done with living flies, maggots did appear.

Redi was also a poet, his best known work being Bacchus in Tuscany.

A crater on Mars was named in his honour.

• Francesco Redi entry in the Catholic Encyclopedia
• Experiments on the Generation of Insects, translation of the 5th edition (1688)

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