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What he did: Redi put meat in three jars: one open, one covered with cloth, and one sealed. He wanted to see if flies would appear. What happened: Flies only came to the open jar, not the others. This showed maggots came from flies, not the meat. -
What he did: Needham boiled broth and left it in jars with loose lids. He wanted to check if tiny life would grow.
What happened: Tiny life (microbes) appeared. He thought this meant life could come from non-living things. -
What he did: Spallanzani boiled broth in jars and then sealed them tightly. He wanted to check if sealing the jars made a difference. What happened: Microbes didn’t grow in the sealed jars, but they grew in open ones. Some people said sealing blocked a "life force" from the air. -
What he did: Pasteur used special bottles with long, curved necks (swan-neck flasks). He boiled broth in them and left the bottles open to air but protected from dust. What happened: No microbes grew in the broth unless the necks were broken. This proved life comes from life, not from non-living things.