For many years, scientists believed in the “Miasma Theory” which suggested that many diseases, such as cholera and the black death, were caused by pollution or bad air. When microscopes were invented, scientists could view very tiny organisms that lived in water and on surfaces all around them. Many scientists believed it was these “germs” that spread disease and not the air. CLAIM
According to "Miasma Theory" many diseases were caused by pollution due to my studies. But now that I have a microscope, I found out people weren't spreading the diseases because of the polluted air, it was because organisms were found in water and on the surface which spreads the disease.
Robert Koch was able to isolate microorganisms from sheep that had contracted anthrax. He grew these bacteria and then injected them in mice. The mice became sick with anthrax. EVIDENCE
if germs were responsible for causing anthrax, then…Sheep and mice that were in the same area would both get sick.REASONING