Answer :
The germ theory of disease was established by Lois Pasteur. He conducted experiments to prove that fermentation is the result of micro-organisms growing on sugar. It proved that spontaneous generation was wrong. Spontaneous generation was the belief that the action of God could cause living organisms to grow from non-living things. Pasteur also proved that micro-organisms from the air were the cause of infectious diseases. Three of his daughters died from infectious diseases. Pasteur proved that these diseases were caused by germs floating in the air. He also helped develop vaccines to help prevent some of these diseases.