The Germ Theory

1
The Germ Theory

• Louis Pasteur finally figures out how diseases
  are spread

2
Existing Theories

• Miasma Spontaneous Generation
• Disease carried by foul air
• Micro-organisms are the result of the process of
  decay
• Pus and gangrene mutates into Germs
• Flies and Maggots provided evidence
• Non-life creates living organisms

3
Micro-Organisms

• Leeuwenhoek
• Dutch clockmaker
• Built an early powerful microscope
• Examined everything he could
• He kept on noticing small living organisms in
  everything he examined
• In food, water, excreta, plaque
• He did not know what function they played

4
Improved Microscopes

• Joseph Lister in the 1830s
• Improved lens production allowed Joseph Lister to
  produce microscopes that could magnify 1,000
  times
• Any scientist could buy this microscope
• Micro-organisms could be studied in more detail

5
Pasteurs Germ Theory

• Pasteur
• A Scientist (not a doctor)
• Brewery in France
• Asked Pasteur to investigate why some vats of
  alcohol would go bad
• His theory
• Germ Germination
• A growing, living organism caused the problem
• His solution to the problem was to boil the
  liquid to kill the germs
• Pasteurisation
• Applied to milk, beer, wine, vinegar

6
Pasteur battles Spontaneous Generation Theory

• French Academy launches competition to prove or
  disprove Spontaneous Generation in 1860
• Pasteur devises experiments to show that microbes
  existed in the air
• Copy source 2 page 129

7
Linking Germs to Disease

• If wine and beer are changed by germs, then the
  same can and must happen sometimes in men and
  animals
• French Silk Industry
• Asked Pasteur to investigate why their silkworms
  kept dying.
• He discovered that a certain germ was responsible
  for

8
Homework Task

• Task page 129
• Draw a flow chart to show how germs were linked
  to disease
• Explain why each step was important
• What factors helped the scientists at each step.

Step Brief Description Why was it Important? Factors that helped development Suitable Image