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Francesco Reddi (1626-1697)
Francesco Reddi (1626-1697) was an italian physician, naturalist and poet, and he was one of the first ever scientists to use controlled experiments to resolve traditional and old beliefs. This was very revolutional at the time, and marked the beginning of the use of evidence methods. Aside from his major contributions in the field of spontaneous generation with maggots and dead meat, he also contributed to parasitology and toxicology, studying the effects of snake venom and parasites on humans. -
Redi's Experiment (1668)
As the first ever experiment involving spontaneous generation, Redi's hypothesis explained that maggots did not appear spontaneously from dead meat, but that they came from eggs laid by flies. To prove his point, he placed the meat in three jars: one open, one sealed and one closed with a gauze. Then, he observed how muggles developed inside. He concluded that maggots appeared only in the open jar, because that's where flies could lay their eggs.Life (maggots) originated from other life (flies). -
John Needham (1713-1781)
John Needham was an English clergyman and naturalist, and his work involved the scientific debates of the Enlightenment era. His experiments were directed to support the theory of spontaneous generation, but they also demonstrated the many mistakes of the past scientific methods. He was also known for explaining his theories with a "godly" factor, to prove the religious belief of the origins of life. -
Lazzaro Spallanzani (1729-1799)
Lazzaro Spallanzani was an Italian Catholic priest, biologist, and physiologist who made many contributions to biology, including studies on reproduction, digestion, and animal behavior. Spallanzani’s work was known for its very serious methods, because he emphasized about the importance of sterilization in between the experiments. This would later have an influence in nowadays techniques, and improve the approachment of the results. -
Needham's experiment (1745)
With his experiment, Needham wanted to prove that the theory of spontaneous generation as the truth. Firstly, he boiled sheep meat soup to kill the microorganisms inside. Then, he transferred the soup with the dead microorganisms to a sealed flask. After, he observed the microbial growth. Microorganisms did in fact appear in the soup, and managed to support his hypothesis. People deeply criticized his method; they believed that both transfer and sealing methods may have contaminated the soup. -
Spallanzani's Experiment (1767)
Lazzaro, who deeply criticized Needham's methods, believed that life did not appear spontaneously, but that it came from air. To do this, he once again boiled soup to kill the microorganisms inside, and placed them in unsealed and sealed flasks. Finally, he compared the microbial growth in both these flasks. No growth appeared in sealed flasks, but it did in the unsealed ones. He concluded that life came from the contamination of the air. -
Louis Pasteur (1822-1896)
Louis Pasteur was a French microbiologist, innovator and chemist. He created the process of pasteurization, created vaccines for diseases such as rabies and anthrax, and established the base for the "germ theory". His work not only ended the debate over spontaneous generation, but also changed the medicine and agriculture industry by demonstrating the role of microorganisms in fermentation and sickness. He is one of the most influential scientists in history. -
Pasteur's Experiment (1861)
Louis Pasteur firmly believed in Redi's conclusion; life comes from life. For his experiment, he used swan-flasks with soup. After, he boiled the soup to sterilize it. Finally, he let the flasks open, but the curve at the top prevented other particles from reaching the soup. As long as it remained intact, the soup was free from microorganisms. When it broke, microbial growth occurred. This means microorganisms are brought by particles in the air, debunking spontaneous generation.