Spontaneous generation and Francesco Redi

Some small organisms are visible to the eye, at least in large numbers. Thousands of years ago, people came up with an explanation for the sudden appearance of mold on bread, maggots on meat, mice in grain: The creatures came to life spontaneously in decaying organic matter.

The theory of spontaneous generation — the belief that under the right circumstances living organisms could come into being without parents — was the target of perhaps the first real scientific experiment, in 1668.

That was the year that the Italian physician Francesco Redi set out to prove his idea that maggots came from eggs laid by flies. This was no fluke: Redi was an intellectual who belonged to prestigious literary societies and undertook many experiments over the course of his life.

Francesco Redi
Francesco Redi

He had also been a member of the Accademia del Cimento, an early scientific society founded by the Medicis in Florence.

Redi set out three groups of jars containing rotting meat. One group he closed completely, one he covered with gauze, and one he left completely open.

As time went on, flies enter the uncovered jars. They landed on the gauze on the partially covered jars. However, there were no flies around the totally covered jars.

Later, many maggots appeared on the meat in uncovered jars. A few maggots appeared on the meat in the partially covered jars. No maggots showed up on the meat in the totally covered jars.

Redi's use of several jars for each situation showed that his results could be replicated, an important aspect of any scientific experiment.

Redi had proved that flies had to be present on or around the meat for maggots to generate. His work began to raise doubts about spontaneous generation, though it was a long time before it was truly put to rest.

Image courtesy of Wikimedia Commons

Pitti Palace, incubator of the scientific method

By 1657, the plague was largely spent and the Catholic Church was becoming a little choosier about its battles, especially given the spread of the Protestant Reformation.

In Italy, the Renaissance was winding down. Science had become so intrinsic to intellectual life that Leopoldo De' Medici, who was both a prince and, later, a Catholic cardinal, opened his private chambers in the Pitti Palace in Florence to a new scientific academy, the  Accademia del Cimento. ("Cimento" means "trial.")

Lion from the Pitti Palace
Lion from the Pitti Palace

Leopoldo and his brother, Grand Duke Ferdinando II of Tuscany, founded, and funded, the academy, which would meet for just 10 years. Its influence would last much longer.

Ferdinando had supported Galileo's experiments and had tried unsuccessfully to nudge the Church toward accepting them in the spirit of exploration. In the 1640s, he opened the Boboli Garden, the grounds of the Pitti Palace, his official residence, to experiments with thermometers, poultry incubators and other instruments.

Galileo's spirit hovered over the academy. Its motto was "provando e riprovando" — "testing and re-testing." Founding members included Galileo's students, like Vincenzo Viviani, who with fellow academy member Giovanni Alfonso Borelli, worked on experiments to pin down the speed of sound waves.

Another member was the physician Francesco Redi, who performed what is considered the first scientific experiment.

Distractions to the patrons, and quarrels among the members, doomed the academy. Its last act was the publication of a compilation of members' work, Examples of Natural Experiments, which in its Latin translation influenced the European scientific community profoundly, becoming essentially the science textbook for at least 100 years.

Image courtesy of Wikimedia Commons