external image Spallanzani2.jpgIn 1770, Lazzaro Spallanzani an Italian priest and a Ph. D in philosophy set out to disprove the long held theory of spontaneous generation, that life could derive from non-living matter. Lazzaro heard about John Needham's experiment with chick broth that 'proved' spontaneous generation, but Lazzaro believed he had discovered a flaw in the experiment making it invalid. When Needham conducted the experiment he heated the chicken broth and then sealed the container, but the broth was exposed to the air before being fully sealed, the introduction of air to the chicken broth is what Lazzaro Spallanzani believed was the flaw in Needhams Experiment. Even though in his experiment John Needham had boiled away the bacteria initially, having exposed the broth once again to air, and bacteria being in the air (although this was unknown at the time) his experiment was flawed. To disprove the Needham experiment, and that spontaneous generation did not in fact exist Lazzaro Spallanzani conducted his own experiment.

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John Needham

To properly and scientifically prove that John Needham’s experiment to prove that spontaneous generation existed, Lazzaro Spallanzani would do a near identical experiment, albeit not allowing the chicken broth to come in contact with the outside air. Lazzaro had two different flasks both of which were heated so that all bacteria would be eliminated from them, Lazzaro had one chicken broth sample come in contact with the air and the other did not. The results of his experiment was that the chicken broth sample that had come in contact with air had life and things growing, the same results Needham had gathered. However Lazzaro’s sample that had not come in contact with air did not have life growing in it at all, proving not only that Needham’s experiment was invalid but that spontaneous generation did not exist. But even though Lazzaro Spallanzani had proven that spontaneous generation did not exist it was still debated and considered possible in some cases.