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Jean-Baptiste van Helmont
Jean Baptiste van Helmont – For abiogenesis. lived from 1579 to 1644
Helmont’s experiment included putting a dirty shirt in a box with wheat seeds, and placing it outside, where mice could get at it. The mice found their way in and he declared that the mice spontaneously generated from the laundry and the seeds. This is flawed for many reasons, including lack of a control, and too many variables -
Francesco Redi
Francesco Redi – Against abiogenesis. lived from 1626 to 1698
Redi’s experiments in 1668 had two jars, both had rotting meat, one set was sealed with wax. The unsealed set had maggots and flies growing in them, but the sealed set were unaffected. Critics said that nothing grew because it wasn’t exposed to air. He then made a third set of jars, these covered with cheesecloth. The third set had fly eggs on top of the jar, but none actually in them. People still didn’t believe him. -
John Needham
John Needham – For abiogenesis. lived 1713 – 1781
John Needham followed similar steps to Spallanzani (rather the reverse, as Needham did it first), but only used one flask, providing no control for the experiment. Either he didn’t heat the flask enough to kill the microbes, or he waited too long for it to cool before he sealed it, allowing microbes to get back in. -
Lazzaro Spallanzani
Lazzaro Spallanzani – Against abiogenesis. lived 1729 – 1799
In 1768, Spallanzani prepared four flasks of broth, two sealed, two unsealed. The first unsealed flask turned cloudy and was found to have microbes in it. So did the first sealed flask. The second unsealed flask was boiled, and left out; it, too, turned cloudy. The second sealed flask (the final flask of all) was boiled and sealed. The broth never turned cloudy, and didn't have any microbes. -
Louis Pasteur
Louis Pasteur – Against abiogensis. lived 1822 – 1895
Pasteurization was named after him, which is heating something (generally food) for a specified amount of time, then cooling it as fast as possible. This was to kill microbes and make sure that something could be stored without microbes growing in it. In his experiment in 1862 to prove abiogenesis didn’t exist, he pasteurized some broth... cont'd -
Louis Pasteur Cont'd
but left it open to air through a long, curved tube; the tube trapped particles and microorganisms as they went in, so nothing could get into the broth except air. After a year, he took the tube off, and the broth had microorganisms growing in it within a day. This showed that even if air could get to something, it wouldn’t just grow microorganisms; they had to exist first, and be introduced. -
Bibliography
http://www.francesco-redi.com/
http://www.newworldencyclopedia.org/entry/Louis_Pasteur
http://en.wikipedia.org/wiki/John_Needham
http://www.ask.com/question/john-needham-s-experiment
http://faculty.sdmiramar.edu/dtrubovitz/micro/history/spallanzani.html
http://www.dinahbarry.pwp.blueyonder.co.uk/sub sites/Spontaneous Generation/background.htm
http://casarcia.com/life/ch01/1-3not2.gif
