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Ancient Beliefs (Until the 17th Century)
Before the 17th Century, there was a theory that life could arise from non-living matter. People believed this due to experiments like putting basil between two bricks in the sun, where they later saw a scorpion and assumed it was spontaneous generation. However, the scorpion likely entered the bricks, attracted by the basil. -
Francesco Redi (1626-1697)
Francesco Redi, an Italian scientist, disproved spontaneous generation in 1668. He placed meat in open, sealed, and gauze-covered jars, showing maggots only appeared in open jars where flies laid eggs. This experiment proved maggots come from flies, not meat, challenging the theory of spontaneous generation. -
Francesco Redi's experiment
In 1668, Francesco Redi's experiment proved wrong spontaneous generation for macroscopic organisms. He placed meat in open, sealed, and gauze-covered jars. Maggots only appeared in open jars where flies could lay eggs, proving maggots come from flies, not the meat. His controlled study showed life originates from pre-existing life. -
John Needham (1713-1781)
John Needham was an English clergyman who supported spontaneous generation. In his experiment, he boiled broth, sealed it in flasks, and observed microorganisms after a few days. He concluded that life arose spontaneously. However, flaws like insufficient boiling and potential contamination led to criticism, and his work motivated further investigations by scientists like Spallanzani and Pasteur. -
John Needham's experiment
John Needham’s 1745 experiment boiled broth inside of no- sealed flasks, and later observed microorganisms, claiming the theory of spontaneous generation. However, flaws like insufficient boiling and contamination led to criticism. His work lead to debates, and later, motivating scientists like Spallanzani to refine methods and disprove his conclusions. -
Lazzaro Spallanzani (1729-1799)
Lazzaro Spallanzani was an Italian biologist who disproved spontaneous generation. In his experiments, he boiled broth in sealed flasks, finding no microorganisms. However, when the flasks were opened, microorganisms appeared, showing that life comes from the air, not spontaneously. Though criticized for removing the "vital force" from the air, Spallanzani’s work laid the foundation for future experiments, including Louis Pasteur’s, that definitively refuted spontaneous generation. -
Lazzaro Spallanzani's experiment
Lazzaro Spallanzani made experiments to disprove spontaneous generation. He boiled broth in sealed flasks, preventing contamination, and observed no microbial growth. When flasks were left open to the air, microorganisms appeared, showing that life came from the air, not spontaneously. Spallanzani’s work provided strong evidence against spontaneous generation and influenced later experiments by Louis Pasteur. -
Louis Pasteur (1822-1895)
Louis Pasteur was a French chemist and microbiologist who disproved spontaneous generation with his swan-neck flask experiment, showing that microorganisms come from the air, not spontaneously. He also developed pasteurization, a method of heating liquids to kill harmful bacteria, and created vaccines for diseases like rabies. Pasteur’s work solidified the germ theory of disease and laid the foundation for modern microbiology, immunology, and public health, transforming science and medicine. -
Louis Pasteur's experiment
Pasteur's swan-neck flask experiment disproved the theory of spontaneous generation. He boiled broth in flasks with long, S-shaped necks, which allowed air in but trapped microorganisms in the neck. The broth remained clear unless the flask's neck was broken, showing that microorganisms came from the air. He concluded that life comes from pre-existing life, not spontaneously. This experiment helped establish the germ theory of disease, and led to pasteurization.