-
Francesco Redi
An Italian physician, poet, and scientist, he was one of the first to use the experimental method in biology. He is known for his contributions to the refutation of spontaneous generation and for his scientific and literary work. -
Redi's Experiment
Redi wanted to prove that worms did not appear spontaneously in rotten meat. He conducted an experiment with three jars: one uncovered, one covered with a thin cloth, and one hermetically sealed. He observed that there were only worms in the uncovered jar, because flies could enter and lay eggs in it. He concluded that the worms came from the flies, not the meat. -
John Needham
An English clergyman and naturalist, he studied microscopy and microorganisms. He defended spontaneous generation based on experiments that showed life in inadequately heated nutrient liquids. -
Lazzaro Spallanzani
An Italian priest and biologist, he investigated reproduction and microorganisms. His rigorous experiments refuted Needham and laid the foundation for demonstrating that life only comes from existing organisms. -
Needham's Experiment
Needham va escalfar un brou fins que bullia, pensant que això eliminaria tots els microorganismes, i després va segellar els matrassos. Al cap d’un temps, va observar que hi havia microorganismes al brou i va concloure que havien aparegut espontàniament. Però no va escalfar el brou prou temps, així que alguns microorganismes van sobreviure i es van multiplicar. -
Spallanzani's experiment
Spallanzani did a more rigorous experiment than Needham. He sealed the flasks before heating them and boiled the broth for a longer time. He found no microorganisms while the flasks were kept sealed. But when he uncapped them, microorganisms quickly appeared. This showed that the microorganisms came from the air, not the broth. -
Louis Pasteur
He was a French scientist who made many important discoveries. He proved that spontaneous generation does not exist with his experiments with special flasks. He is also known for his research on fermentation, pasteurization, and the rabies vaccine. -
Pasteur's Experiment
Pasteur perfected his experiments with his swan-neck flasks. He boiled the broth in the flask and let air in, but thanks to the curved neck, the particles in the air were trapped and did not contaminate the liquid. The broth did not show life for a long time, but when he broke the neck of the flask or tilted the liquid towards the part with particles, microorganisms appeared. This showed that life came from microorganisms in the air, not from a life force.