During his experiments in the 1860s, French chemist Louis Pasteur developed modern germ theory. He proved that food spoiled because of contamination by invisible bacteria, not because of spontaneous generation.

Louis Pasteur Discovers Germ Theory, 1861. During his experiments in the 1860s, French chemist Louis Pasteur developed modern germ theory. He proved that food spoiled because of contamination by invisible bacteria, not because of spontaneous generation. Pasteur stipulated that bacteria caused infection and disease.

Who invented germ theory of disease? Still, it has been little more than a century and a half since Robert Koch made the discoveries that led Louis Pasteur to describe how small organisms called germs could invade the body and cause disease.

In the final decades of the 19th century, Koch conclusively established that a particular germ could cause a specific disease. He did this by experimentation with anthrax. Using a microscope, Koch examined the blood of cows that had died of anthrax. He observed rod-shaped bacteria and suspected they caused anthrax.

germ theory, in medicine, the theory that certain diseases are caused by the invasion of the body by microorganisms, organisms too small to be seen except through a microscope. The French chemist and microbiologist Louis Pasteur, the English surgeon Joseph Lister, and the German physician Robert Koch are given much of the credit for development and acceptance of the …

Various germ theories, sometimes known as “animacular” theories, had been proposed for hundreds of years before 1850. An animalcular theory, published in 1658, can be found in Athanasius Kircher’s Scrutinium Physico–Medicum Contagiosae Luis. In the 19th century, the animacular theory was associated with an outdated past.