Spontaneous Generation

By reeen
  • 400 BCE

    History of Animals

    History of Animals
    Aristotle publishes History of Animals. In which it discusses his theory on how some organisms are given birth to from a parent while others spontaneously appear in the right environmental situations. This is known to be the first real documentation showing the belief of spontaneous generation.

  • A Challenge in Italy

    A Challenge in Italy
    Italian scientist, Francesco Redi, is the first to disprove spontaneous generation by conducting an experiment that dealt with 3 jars of meat. One was sealed completely, one was covered with gauze, and the last was left out in the open. Through this experiment, Redi was able to prove that maggots hatched from eggs laid on the gauze and meat.

  • Needham and Gravy

    Needham and Gravy
    John Needham creates a rebuttal towards Redi’s results, challenging experiment.
    Needham created in experiment in which mutton gravy was boiled so that all living organisms that could've been in it were supposedly killed. After this, the flasks containing gravy were sealed and a couple days later, microbes such as mold could be seen growing on the gravy.

  • Spallanzani Challenges Needham

    Spallanzani Challenges Needham
    Lazzaro Spallanzani conducted a similar experiment. He boiled bottles of broth. One was sealed and one was kept open. He almost succeeded to prove that spontaneous generation was not a viable theory. Results showed that the bottle that wasn’t sealed had no life while the other had signs of small organisms. However, he had removed all the air from the sealed bottle of broth which created an argument since it was thought that air was needed in order for spontaneous generation to occur.

  • The Final Blow

    The Final Blow
    Louis Pasteur designed bottles with an S-shaped neck that pointed downward. His goal was to recreate Spallanzani’s experiment in a way that allowed air. The new bottles blocked microbes out due to gravity. He then boiled the broth and was able to leave it out for an entire year without any traces of life in it. Pasteur then broke off the neck of the bottle so that foreign organisms were able to enter the broth. Within a couple days, microbes started growing in the broth.