Germ Theory and Its Applications to Medicine and on the Antiseptic Principle of the Practice of Surgery

by Louis Pasteur

Before the introduction of antisepsis and inoculation, people commonly died due to unsanitary conditions in the home, or following surgery or childbirth. Between them, the great scientists Louis Pasteur (1822-1893) and Joseph Lister (1827-1912) extended widely the practice of inoculation and revolutionized medical practice. Pasteur's discovery that living organisms are the cause of fermentation formed the basis of the modern germ theory. Following Pasteur's researches, Lister proceeded to develop his antiseptic surgical methods. These breakthroughs in medicine are to be reckoned among the greatest discoveries of the nineteenth century.

Genres: Science, Nonfiction, Biology

144 pages, Paperback

First published May 1, 1996

About the author

Louis Pasteur was a French chemist and microbiologist born in Dole. He is remembered for his remarkable breakthroughs in the causes and preventions of disease. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies. His experiments supported the germ theory of disease. He was best known to the general public for inventing a method to stop milk and wine from causing sickness, a process that came to be called pasteurization. He is regarded as one of the three main founders of microbiology, together with Ferdinand Cohn and Robert Koch. Pasteur also made many discoveries in the field of chemistry, most notably the molecular basis for the asymmetry of certain crystals. His body lies beneath the Institute Pasteur in Paris in a spectacular vault covered in depictions of his accomplishments in Byzantine mosaics.

Reviews

[Steven H · Rating 5 out of 5]

PASTEUR’S EXPERIMENTS ON HYGIENE, ‘SPONTANEOUS GENERATION’, etc.

Louis Pasteur (1822-1895) was a French chemist and microbiologist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization. He wrote in the Preface to this 1879 book, “I am convinced that I have found a precise, practical solution of the arduous problem which I proposed to myself---that of a process of manufacture, independent of season or locality, which should obviate the necessity of having recourse to the costly methods of cooling employed in existing processes, and at the same time secure the preservation of its products for any length of time. The new studies are based on the same principles which guided me in my researches on wine, vinegar, and the silkworm disease… The etiology of contagious diseases may, perhaps, receive from them an unexpected light.” (Pg. 15)

He explains, “fermentation is a very general phenomenon. It is life without air, or life without free oxygen, or, more generally still, it is the result of a chemical process accomplished on a fermentable substance capable of producing heat by its decomposition, in which process the entire heat used up is derived from a part of the heat that the decomposition of the fermentable substance sets free.” (Pg. 48)

He describes an experiment: “If we completely fill a flask of a few litres capacity… with the liquid described, taking care to also have the delivery-tube also filled, and its opening plunged under mercury, and, forty-eight hours afterwards by means of a chloride of calcium bath, expel from the liquid on the surface of the mercury all the gas which it holds in solution, this gas, when analyzed, will be found to be composed of a mixture of nitrogen and carbonic acid gas, without the least trace of oxygen. Here, then, we have an excellent means of depriving the fermentable liquid of air…

"We may wait even longer; and then, if the liquid does not become impregnated spontaneously with vibrio germs, the liquid, which at first was turbid from the presence of bacteria, will become bright again, since the bacteria, deprived of life, or, at least, of the power of moving, after they have exhausted all the oxygen in solution, will fall inert to the bottom of the vessel.” (Pg. 71)

He observes, “In our Memoir of 1862, on so-called SPONTANEOUS generations, would it not have been an entire mistake to have attempted to assign specific names to the microscopic organisms which we met with in the course of our observations? Not only would we have met with extreme difficulty in the attempt, arising from the state of extreme confusion which even in the present day exists in the classification and nomenclature of these microscopic organisms, but we should have been forced to sacrifice clearness in our work besides; at all events, we should have wandered from our principal object, which was the determination of the presence of absence of life in general, and had nothing to do with the manifestation of a particular kind of life in that of that species, animal or vegetable.” (Pg. 88)

This book may interest students of the history of science.

[Keith · Rating 4 out of 5]

Louis Pasteur’s Germ Theory (1878) is included in volume 38 of The Harvard Classics, a volume dedicated to the history of science. Pasteur was a hero, whose scientific work helped lead to the development of hygiene practices in medicine, vaccines for a variety of medical disorders, and, of course, the Germ Theory of Disease. In a time when basic principles of medicine and science are being ignorantly attacked in countries such as the United States, it is all the more important to read works such as this.


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[Image: Cover of the Delphi Classics’ The Harvard Classics]

Citation:
Pasteur, L. (2018). Germ theory. In C. W. Eliot (Ed.), The Harvard classics [eBook]. Delphi Classics. https://www.delphiclassics.com/shop/t... (Original work published 1878)

Title: Germ Theory
Author(s): Louis Pasteur
Year: 1878
Series: The Harvard Classics (1909): Volume 38 - Delphi Complete Harvard Classics and Shelf of Fiction
Genre: Nonfiction - Scientific Paper
Date(s) read: 10/18/25
Book 217 in 2025
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[Josiah Richardson · Rating 3 out of 5]

This man and his work has saved countless lives through aseptic techniques that reduces nosocomial infections dramatically, as well as his pasteurization techniques still applied today in many beverages.

[Carter Reads Classics · Rating 5 out of 5]

Loved it!

[Jonathan Morrow · Rating 3 out of 5]

These guys are science heroes to me, so I just enjoyed reading some of their original work. It's pretty dry, but as long as you don't get bogged down in trying to follow Pasteur's exact calculations, it's not a very difficult read. There are several nuggets in here that give some insight into how Pastuer conducted his scientific explorations, and how he engaged with the scientific community when sharing his results. Kind of fascinating, really. If that sort of thing doesn't interest you though, no reason to read this. Also, be aware that Lister's paper is very short, so ~90% of the book is Pasteur's work.