proved it

• Pasteur proved his theory by placing sterile

  water in a sealed flask and then placing sterile

  water in an open flask.
• This proved that there were germs in

  the air which caused disease.
• The closed flask stayed sterile
• But the open flask bred germs.
• By

  heating liquid, it killed the germs. He proved this by

  placing liquid in a swan neck flask. The air could not get to

  the liquid, but it could if the neck was broken. This

  proved germs caused decay.