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Redi's Experiment p2
In the below picture we can check what happened in each different jar. So with this experiment Redi could demonstrate that the maggots come from fly eggs and that they are not a spontaneous generation. They are attracted by the meat some time before, we have demonstrated it because when we sealed it with something maggots do not enter through the rotting meat. -
Redi's Experiment p1
In 1668, Franceso Redi, an Italian scientist, designed the first scientific experiment to test the spontaneous generation. At that time it was widely held that maggots arose spontaneously in rotting meat. So he decided to do the experiment based on it. He did the experiment by placing fresh meat in each two different jars. In the first two he didn’t do anything to see what naturally happened. The second jars were sealed, and the third jars was covered with cloth netting. -
Needham’s rebuttal
So it was in 1745 when John Needham, an English clergyman said that spontaneous generation occurs when he said the definitive experiment. What Needham did was to put heat into a flask and boil it until he killed the microorganisms. After boiling it, he sailed the flask and he waited until the results. Then he saw that microorganisms were present in the flask so he said that the spontaneous generation was true. -
Needham's rebuttal
Before Red’s experiment Needham didn’t believe everything he thought occurred under some circumstances. So when the microscope was invented he wanted to improve is belief. With a microscope they could also discover the microorganisms. So some scientists said that spontaneous generation was not applied to big and large organisms like maggots, they thought it was applied to small microbes. -
Criticism from Spallanzani
After boiling it he sealed it for some time more and then he uncovered it and the microorganisms grew in the broth again, but they were coming from the contaminated air so he concluded that spontaneous generation was false. -
Criticism from Spallanzani
Lazzaro Spallanzani was an Italian priest that disagreed with Needham’s conclusions of the experiment. So he decided to do the experiment to see if this was true. He did mostly the same experiment changing some things. Firstly, he poured broth into flasks as Needham did, but he sealed it while he was boiling it. Boiling it, he killes the present organisms. -
Pasteur puts spontaneous generation to rest
Louis Pasteur was a notable French scientist that re-created the experiment. He designed some bottles with the S curved shape necks oriented downward. He putted a nutrient-enriched broth in one of those bottles. He boiled it and observed that there was no life in the jar during 1 year. -
Pasteur puts spontaneous generation to rest
Then he broked up the top of the bottle and he exposed the air and the particles. And then on some days he saw some life forms in the broth. So then he could know that the contamination doesn’t come from “life force” it comes from the life forms in the air.