Finally, Germ theory was accepted.
Koch developed a new experimental method to test whether a particular micro-organism is the cause of a disease. Building on Pasteur's work on germ theory, Koch used experiments to prove that the bacterium Bacillus anthracis was the cause of anthrax - the bacterium could be observed in the tissue of anthrax victims. He extracted this bacterium from a sheep which had died of anthrax, grew it and injected a mouse with it. The mouse developed the disease as well. Koch repeated this process over 20 generations of mice, before he announced in 1876 that he had proved this bacterium caused anthrax.