Francesco Redi was an Italian physician who was the first to attempt to disprove the Theory of Spontaneous Generation by performing a controlled experiment. A controlled experiment is an experiment in which you change just one thing to find out the result.

In 1668, Francesco Redi performed an experiment to check whether maggots (baby flies) really came from decaying meat.

He did this by placing meat in a number of jars and covering half of them with fine gauze while leaving the others uncovered.

Maggots developed only on the meat in the uncovered jars.

From this, Redi concluded that the maggots did not come from the meat, but from tiny eggs that flies had laid on the meat.

Since the flies could not land on the meat in the covered jars, they could not lay eggs on that meat, and no maggots formed.

Therefore, decaying meat could not produce maggots. Only flies could produce maggots.

Soon other scientists were able to repeat Redi's experiment, so many were convinced that living things can not come from nonliving things.

Later, Lazzaro Spallanzani performed a similar experiment with broth.