What did people believe caused disease by 1800? Miasmas Supernatural However, by 1800 most scientists and doctors knew about the existence of micro-organisms. However, they thought they were the RESULT of disease, NOT the cause of it. This was called the theory of spontaneous generation

Lesson Objectives To identify what people believed caused disease in 1800 To identify and explain the key features of Germ Theory To evaluate whether Germ Theory was a ‘turning point’

How did Louis Pasteur discover germ theory? Pasteur was a French chemist In 1857 he was asked to investigate why sugar beet, used to make alcohol, often went sour during fermentation so could not be used. Pasteur examined samples of the sour liquid under a microscope. He thought that souring was caused by germs in the air He proved this by experimenting with water in a swan neck flask.

Was Pasteur’s discovery a turning point? Pasteur used scientific approach to successfully prove his findings in public But many people still refused to believe it. Some still clung to the spontaneous generation theory Other doctors and scientists saw that he had made a definite link between germs and decay