Little Bits of History

Germ Theory

Posted in History by patriciahysell on April 20, 2013
Louis Pasteur

Louis Pasteur

April 20, 1862: Louis Pasteur and Claude Bernard complete their first test demonstrating a new theory. Long ago it was believed diseases were spontaneously generated or without prior cause. Others theorized “minute bodies” invaded a person and caused a disease. Contagion was seen as a method of transfer of the tiny creatures, but the creatures remained unseen. Experiments were set up and spontaneous generation was shown to be impossible.

Pasteur was not the first to propose germ theory as a contagion method. He did, however, conduct easily reproducible experiments and was influential in convincing others of the validity of the theory. He proved some germs were responsible for fermentation. Some of the tiny invaders were present from the beginning and some were airborne. By a process of heating most germs present in raw milk would be killed, making the milk safer. The process, called pasteurization, was proven on this date. It is not the same as sterilization, which kills all pathogens.

Claude Bernard, French physiologist, was a proponent of the scientific method. By rigorous methodology he debunked many of the “truths” of his day. He studied the pancreas and liver and proved the existence of vaso-motor nerves. He advanced the theory of homeostasis, or the process by which the body regulates functions in response to external environmental influences. He sought clarification by any method and used vivisection, a practice which prompted his wife to leave him and to actively campaign for its eradication.

Louis Pasteur went on to study vaccines. He worked first with chickens to eradicate avian cholera. He then developed an anthrax vaccine for cattle. Edward Jenner had used cowpox, a less virulent disease, to protect against smallpox, an often lethal disease. Pasteur furthered the idea by artificially weakening the causative agent. A rabies vaccine was developed and used on 9-year-old Joseph Meister on July 6, 1885. The boy lived. The Pasteur Institute was established on July 4, 1887 and continues to expand medical knowledge with about 250 scientists teaching and mentoring 800 students at the Institute each year.

“When we meet a fact which contradicts a prevailing theory, we must accept the fact and abandon the theory, even when the theory is supported by great names and generally accepted.” – Claude Bernard

“The constancy of the internal environment is the condition for a free and independent life.” – Claude Bernard

“Science knows no country, because knowledge belongs to humanity, and is the torch which illuminates the world. Science is the highest personification of the nation because that nation will remain the first which carries the furthest the works of thought and intelligence.” – Louis Pasteur

“There does not exist a category of science to which one can give the name applied science. There are science and the applications of science, bound together as the fruit of the tree which bears it.” – Louis Pasteur

This article first appeared at in 2010. Editor’s update: The Pasteur Institute is a French non-profit foundation. It was founded as stated above and inaugurated on November 14, 1888. They have remained vigilant in fighting infectious diseases. The Institute was the first to isolate HIV, the causative virus behind AIDS, back in 1983. They are based in Paris and between 1908 and 2008, eight Pasteur Institute scientists have been the recipients of the Nobel Prize for medicine physiology with two scientists sharing the 2008 award. They have done definitive research into diphtheria, tetanus, TB, polio, influenza, yellow fever, and plague. The Institute was active during both World Wars not only in the prevention of sanitary risks, but also in dealing with the demands of a stressed culture and environment. Their most critical task was vaccinating the troops against typhoid fever which was easily contracted because of standing pools of water.

Also on this day: Whodunit? – In 1841 the first mystery story is published.
Ludlow Massacre – In 1914, mining riots took place in Colorado resulting in 22 dead.
Two – In 1964, BBC2 launched.