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title: "History of experiments"
chunk: 3/3
source: "https://en.wikipedia.org/wiki/History_of_experiments"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:39:12.087908+00:00"
instance: "kb-cron"
---

The French biologist Louis Pasteur (1822-1895), regarded as the "Father of microbiological sciences and immunology", worked during the 19th century.  He postulated - and supported with experimental results - the idea that disease-causing agents do not spontaneously appear but are alive and need the right environment to prosper and multiply.  Stemming from this discovery, he used experimentation to develop vaccines for chicken cholera, anthrax and rabies, and developed methods for reducing bacteria in some food products by heating them (pasteurization).  Pasteur's work also led him to advocate (along with the English physician Dr. Joseph Lister) antiseptic surgical techniques. Most scientists of that day believed that microscopic life sprang into existence from spontaneous generation in non-living matter.
Pasteur's observations of tiny organisms under the microscope caused him to doubt spontaneous generation. He designed an experiment to test his hypothesis that life could not arise from where there is no life. He took care to control possible confounding factors. For example, he needed to make sure there was no life, even microscopic, in the flasks of broth he used as a test medium. He decided to kill any microscopic organisms already present by boiling the broth until he was confident that any microorganisms present were dead. Pasteur also needed to make sure that no microscopic organisms entered the broth after boiling, yet the broth needed exposure to air to properly test the theory.  A colleague suggested a flask with a neck the shape of an "S" turned sideways. Dust (which Pasteur thought contained microorganisms) would be trapped at the bottom of the first curve, but the air would flow freely through.
Thus, if bacteria should really be spontaneously generated, then they should be growing in the flask after a few days. If spontaneous generation did not occur, then the contents of the flasks would remain lifeless. The experiment appeared conclusive: not a single microorganism appeared in the broth. Pasteur then allowed the dust containing the microorganisms to mix with the broth. In just a few days the broth became cloudy from millions of organisms growing in it. For two more years he repeated the experiment in various conditions and locales to assure himself that the results were correct. In this way Pasteur supported his hypothesis that spontaneous generation does not occur. Despite the experimental results supporting his hypotheses and his success curing or preventing various diseases, correcting the public misconception of spontaneous generation proved a slow, difficult process.
As he worked to solve specific problems, Pasteur sometimes revised his ideas in the light of the results of his experiments, as when faced with the task of finding the cause of disease devastating the French silkworm industry in 1865.  After a year of diligent work he correctly identified a culprit organism and gave practical advice for developing a healthy population of moths.  However, when he tested his own advice, he found disease still present. It turned out he had been correct but incomplete – there were two organisms at work.  It took two more years of experimenting to find the complete solution.

== See also ==
List of experiments

== References ==

Bell, Madison Smartt (2005) Lavoisier in the Year One.. W.W. Norton & Company, Inc. ISBN 0-393-05155-2
Borlik, Todd Andrew (2013). "More than Art: Clockwork Automata, the Extemporizing Actor, and the Brazen Head in Friar Bacon and Friar Bungay". In Hyman, Wendy Beth (ed.). The Automaton in English Renaissance Literature. Ashgate Publishing, Ltd. ISBN 978-1-4094-7884-3.
Holmes, Frederic Lawrence (1987) Lavoisier and the chemistry of life: an exploration of scientific creativity, Univ. Wisconsin Press. Reprint. ISBN 978-0-299-09984-8.
Dubos, Rene J. (1986) Louis Pasteur: Free Lance of Science. Da Capo Press. ISBN 978-0-306-80262-1
Kupelis, Theo; Kuhn, Karl F. (2007) In Quest of the Universe. Jones and Bartlett Publishers. ISBN 978-0-7637-4387-1.