Unmasking the Untruths
Francesco Redi lived in Italy during the 1600s. At the age of 21, he earned doctoral degrees in both medicine and philosophy from the University of Pisa. For the next 50 years he was the physician and pharmacist to the leading families of Florence. His hobby was disproving myths by performing experiments with animals including snakes and flies.
At that time, people believed that snake venom was produced in a gallbladder and was poisonous if swallowed. With controlled experiments, he disproved these myths. He demonstrated that venom came from the fangs and would only poison a person if bitten. While he was at it, he showed how a tourniquet could prevent the venom from reaching the heart.
Also at that time, people believed in "spontaneous generation". Specifically, they believed that maggots appeared spontaneously in rotting meat. An unpleasant miracle of life, they thought. But they were wrong.
Redi placed animal flesh (veal) in an open jar and in a closed jar. Flies showed up. In the open jar, they landed on the veal. After several days, maggots appeared. But in the closed jar no maggots appeared. And he used gauze as the cover for the closed jar to show that "fresh" air was not a factor.
He continued his experiments by capturing the maggots and waiting for them to metamorphose into flies. He demonstrated the circle of life for flies: from fly to egg to maggot to fly. Rotting meat was the convenient incubator, not the miraculous source.
And, to put the final nail on the coffin of the theory of spontaneous generation, he placed dead flies and dead maggots in sealed jars with veal. No maggots appeared. But when the same thing was done with living flies, maggots did appear.
A lot was proven with only a little bit of veal.
Redi was careful to express his results in a way that did not contradict the teachings of the Roman Catholic Church. He always stated his conclusions based on biblical passages, such as his famous adage: Omne vivum ex vivo (All life comes from life). So, unlike Galileo, he stayed out of trouble. Smart man.
Note: Just because Doctor Francesco Redi was a trail-blazing science geek didn't mean he had no other interests. For example, the man enjoyed his wine. His playful poem, Bacchus in Tuscany, glorifies the wine of that region, and it's still read in Italy today.