Final answer:
Francesco Redi's experiment in 1668 disproved the theory of spontaneous generation by showing that maggots only appeared on meat when flies had access to it.
Step-by-step explanation:
Francesco Redi experimented in 1668 to disprove the theory of spontaneous generation. He placed the meat in three sets of jars: one set was open to the air, one set was covered with gauze, and one set was tightly sealed. Maggots only appeared on the meat in the open jars, while none were found in the covered or sealed jars. This experiment demonstrated that maggots only form when flies are allowed to lay eggs in the meat, refuting the idea of spontaneous generation.