The idea of spontaneous generation was disproved by

in an experiment involving jars of meat.

Francesco Redi

Jan Baptista van Helmont

Aristotle

The idea of spontaneous generation hypothesis was disproved by Francesco Redi through an experiment where he observe generation of maggots from a piece of meat that was left open.

Explanation:

In 1668, Francesco Redi have done this experiment by using 3 pieces of meat. The first piece of meat was left open so that flies can lay eggs. With the second piece of meat, he uses a cheesecloth and observed that flies lay egg into cheese cloth but when he removed the cloth, no maggots developed. And with the last piece of meat, he placed a paper under which the meat was kept. In that case he have noticed that flies didn't lay any eggs and thus no maggots developed. This above experiment gave him the idea of spontaneous generation hypothesis.