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400
Belief of Spontaneous Generation
During Aristotle's time, scientists and common folk believed that simple living organisms came from non-living objects. It was common sense that simple organisms such as bugs, frogs, and other animals could spawn from mud, dust, food, etc. (400 BC) -
Development and Modification of the Microscope
Development and modification of the microscope allowed people to see new life forms like yeast, fungi, bacteria, and protists. People didn't know where these small organisms came from and it seemed as if these organisms spontaneously arose from non-living things like spoiling meat or muddy soil. (1600s) -
Francesco Redi experiment with flies and meat
Francesco Redi, Italian physician did an experiment with flies and open/sealed jars containing meat carcasses. It is known as the first real experiment with control groups, observations, questions, a hypothesis, a prediction, testing, data, and a conclusion(1668) -
John Needham experiements with soups
John Needham, Scottish clergyman and naturalist displayed how microorganisms thrived in soups that were exposed to the air. He believed that there was “life force” in the molecules in air and the oxygen in it (inorganic matter). This is what caused spontaneous generation. He claimed that microorganisms arise spontaneously from heated broth. He said it supported spontaneous generation(1745-1748) -
Lazzaro Spallanzani tried some variations on Needham's soup experiments
Lazzaro Spallanzani, Italian abbot and biologist, tried some variations on Needham’s soup experiments. He found that boiling soup for an hour and sealing it shut could sterilize the soup and prevent anything from growing. He suggested that Needham’s results were because of living things in the air, entering his broth before sealing the flasks. No growth occurred during that time. He argued that air was required for spontaneous generation. (1765-1767) -
Rudolf Virchow introduced the concept of biogenesis
Rudolf Virchow introduced the concept of biogenesis meaning that living cells can arise from preexisting cells only (or life can only come from life). (1858) -
Louis Pasteur conducts an experiement disproving spontaneous generation
Louis Pasteur conducted an experiment disproving spontaneous generation in microscopic organisms. Pasteur boiled broth in different flasks to sterilize it, then he let them cool. As the broth and air in the containers cooled, fresh room air was put into the containers. All of the flasks were open to the outside air. In the straightened up open flasks, the contents spoiled. In the S shaped neck flasks or cotton plugs that filtered out bacteria flasks the air the broth did not spoil. (1859) -
Pasteur's theory accepted by France's Academy of Sciences
Louis Pasteur’s theory was accepted by France’s Academy of Sciences. (1864)
