Answer:
The theory of spontaneous generation was suggests that the living organisms can come from inanimate objects, however it is an obsolete theory that is disproved by many experiments. The very first experiment that disapproved it was the experiment by Francesco Redi in 1668.
He demonstrated that maggots come from the eggs of flies instead of rotting meat. He placed raw meat inside of every jar. Half the jars he left open and the other half, he covered with mesh. In open jars he found maggots after some time but covered jars have no maggots. That proved that the maggots come from eggs of flies rather than rotten meat.