Pasteur's experiments on spontaneous generation, c 1857.
© Science Museum / Science & Society Picture Library
This glas flask filled with broth is a replica of one used by the French chemist and microbiologist Louis Pasteur (1822-1895) in his experiments to show that germs are the cause of disease and decay. In order to prove that germs are present in air and will grow in a sterile nutrient medium, Pasteur boiled broth in glas flasks and sealed the ends to prevent air from entering. The broth stayed unspoilt until the flasks were opened, proving Pasteur's theories. Pasteur developed the pasteurisation proces which kills pathogens in milk, wine and foods, and he produced vaccines against anthrax and rabies.