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Francesco Redi (1668)
Redi placed meat in three types of jars: uncovered, sealed, and covered with a cloth.
Result: Only the uncovered jar had maggots, proving that flies laid eggs on the meat, not that life appeared on its own.
Conclusion: Life does not come from non-living matter for larger organisms like maggots. -
John Needham (1745)
Needham heated broth, sealed it, and saw microorganisms appear after some time.
Result: He thought this showed life could arise spontaneously in smaller organisms.
Problems: The broth may not have been heated long enough, and the flasks might not have been sealed properly. -
Lazzaro Spallanzani (1765–1779)
Spallanzani repeated Needham’s experiment but boiled the broth longer and sealed the flasks before boiling.
Result: No life appeared in sealed flasks, but life grew after opening them.
Conclusion: Microorganisms came from the air, not from spontaneous generation.
Difference from Needham: Better sealing and longer boiling to prevent contamination. -
Louis Pasteur (1859–1864)
Pasteur used flasks with long swan-neck tubes, boiling broth inside and leaving the necks to trap particles from the air.
Result: No life appeared as long as the necks stayed intact. When broken, life forms grew in the broth.
Conclusion: Microorganisms come from the air, proving life only comes from other living things.
Significance: Pasteur’s work ended the belief in spontaneous generation and established that life comes from existing life.