GERM THEORY

1
GERM THEORY
2
AIMS

• To understand the concepts of germ theory and
  spontaneous generation.
• To see how the theories developed.
• To understand why germ theory was so important.

3
HOW ARE DISEASES CAUSED?

• We now know that diseases are caused by germs.
• In the 1800s the popular explanation was miasma
  bad air that caused illnesses.
• The air came from rubbish and decaying food and
  was blown on the wind.

4
SPONTANEOUS GENERATION

• Using early microscopes, people found
  micro-organisms on everything they studied.
• Many people believed the organisms were the
  result of decay.
• Decaying matter turns into living organisms.
• Flies and maggots that were seen on decaying
  matter were created by it.

5
GERM THEORY

• In the 1850s Louis Pasteur, a French scientist,
  began studying micro-organisms.
• He developed a theory that the micro-organisms
  were causing the decay not the other way round.
  
• In 1861, Pasteur proved that his germ theory was
  correct.

6
If wine and beer are changed by germs, then the
same can and must happen sometimes in men and
animals.
7
IMPORTANCE

• Pasteur speculated that disease could be caused
  by the same process that made wine go sour or
  material decay.
• Pasteur was a scientist, not a doctor. He had not
  proved the link between germs and disease.
• Much remained to be done, but the link had been
  made.

8
TASK

• Explain the theory of spontaneous generation.
• Explain germ theory.
• Why was Pasteur so important?
• What remained to be done after Pasteurs
  discovery in 1861?