Spontaneous Generation

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Spontaneous Generation

• Notes
• Biology

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Spontaneous Generation

• Aristotle
• Francisco Redi
• Von Leewehoek
• Needham
• Spallani
• Pasteur

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1-2 How scientists work

• 2300 years ago, Greek philosopher Aristotle made
  extensive observations of the natural world.
  During his lifetime people thought that special
  vital forces, could bring living things from
  non-living things

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400 years ago..

• People started to challenge that
• Did maggots really appear from meat?

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Mice from grain?
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Beetles from dung?
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True or False_ theory?

• The idea that this can happen is called
  spontaneous generation.

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Francisco Redi

• Wanted to test the maggot in meat theory. How can
  we set up this experiment?
• Controlled variables? Manipulated variable?
  Responding variable?

Controlled Variables temp, light, types and size
of meat, time, location Manipulated Variables
gauze that covered the jar Responding variable
whether maggots appear or not
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• 1600s Redi (italian) meat in the jar

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• 1600s VonLeewenhoek (Netherlands)- sees
  animacules under a microscope

                                                 
Antonie van Leeuwenhoek 
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• 1700s Needham (English) boils broth leaves it
  sealed and sees growth

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• Lazzaro Spallanzani (italian)- Needham did not
  heat it enough!!! He did the broth experiment
  again and did not get growth!!
• And people still argued you need air for life!!

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Louis Pasteur

• Argument against Spallanzani was that air was
  needed for spontaneous generation
• So Pasteur decided find a way that added air
  without adding animacules.

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• Pasteurization is a process by where a substance
  is boiled to kill most of the micro-organisms and
  then refrigerated to slow regrowth. Ask me for
  the story about my mom