Francesco Redi presented a cell theory which helped to discredit the idea that living things can come from non-living things. Born in Italy, his 17th century experiments were just one aspect of his life. He was a published poet, a working physician, and an academic while pursuing a passion in science.
What made Redi’s work so notable was the fact that he relied on the information that controlled experiments could provide.
The Experiment by Francesco Redi
In the early days of science, people relied on what their senses told them. If a person couldn’t see something happen, then it was assumed that nothing happened. Therefore, if someone were to leave meat outside in the heat and allow it to spoil, the maggots that would eventually come out of the meat were a “spontaneous” occurrence.
What Redi wanted to do was disprove the idea that living things could be spontaneously generated from non-living cells. To do this, he created a controlled experiment.
The experiment by Francesco Redi was quite basic. He took 6 jars and placed a piece of meat into all of them. He would then cover 3 of the jars with muslin and leave the other 4 uncovered. As one might guess, maggots developed in the uncovered jars, but did not develop in the jars that were covered.
Why? Because the maggots are a life-stage of the fly, which Redi would document when reporting his findings.
Then Redi continued the experiment. He left just one jar uncovered, while covering two others. One was covered in cork, while the other was covered in gauze. The flies could not get through the cork, but they did reproduce on top of the gauze. This allowed Redi to show the maggots on top of the gauze, not in the jar with the cork, and on the meat with the open jar.
It is this controlled process, where ideas can be compared to one another so that findings can have evidence to support them, that has become part of the science since this initial experiment.
He was able to provide this type of experiment because of past work with snake venom. There were many misconceptions about what would happen to a person when exposed to venom. Redi would show people that venom came from a fang, in the form of a yellow fluid. He showed that tight ligatures bound around the wound could prevent passage of the venom to the heart.
And, perhaps most importantly, he showed that the venom was dangerous if it entered the bloodstream, countering the popular idea that venom is poisonous if swallowed or that one could eat the head of a viper and have an effective antidote.
His early works and theories helped to create the field of experimental toxicology. His later works would help to establish the benefits of controlled experiments. He would then take these experiences and expand upon them further, helping to show people that even the smallest forms of life could still produce life on their own without spontaneity.
Francesco Redi and Parasitology
Francesco Redi, through his work on disproving spontaneous generation, became quite familiar with various insects. He published a book called Esperienze Intorno all Generazione degl-Insetti that offers several relevant illustrations of tiger ticks, deer ticks, and the first descriptions of certain larva that are a life-stage of deer flies. He would also be the first to describe the sheep liver fluke.
In total, Redi helped to improve the knowledge in parasitology through descriptions of almost 200 different species.
Through these observations, he was able to show that parasites produce eggs. Those eggs develop into a larva stage, which then eventually turns into an adult stage parasite.
The reason why Redi went to this level of documentation and description was because his work was occurring at the same time as the work of Galileo. The power of the church was immense at the time and people were being jailed or killed for apostasy when presenting scientific theories that ran counter to what was believed to be in the Bible. Redi saw what was happening to Galileo and ensured that his work could be scientifically sound without presenting a theological question of doubt.
His most famous adage, in fact, that “all life comes from life,” is based on a passage of scripture, just as much of his work. That association helped him become an established name in the scientific community without receiving the same threats from the church that other thinkers happened to encounter.