11.LOUIS
PASTEUR 1822 - 1895.
The French chemist and biologist
Louis Pasteur is generally acknowledged to be the most important single figure
in the history of medicine. Pasteur made
many contributions to science, but he is most famous for his advocacy of
the germ theory of disease and for his development of the technique of
preventive inoculation.
Pasteur was born in 1822, in the town
of Dole, in eastern France. As a college student in Paris, he studied science.
His genius was not evident during his
student days; in fact, one of his professors recorded him as
"mediocre" in chemistry. However, after receiving his doctorate in
1847, Pasteur soon showed that his professor's judgment had been in error. His
research on the
He then
turned his attention to the study of fermentation, and showed that that process is due to the action of certain types
of microorganisms. He also demonstrated that the presence of certain other
species of microorganisms could produce undesirable
products in the fermenting beverages. This soon led him to the idea that
some species of microorganisms could pro-duce
undesirable products and effects in human beings and other animals.
undesirable products and effects in human beings and other animals.
Pasteur was not the first person to suggest the germ
theory of disease. Similar hypotheses had been
advanced earlier by Girolamo Fracastoro, Friedrich Henle, and others. But it
was Pasteur's vigorous championship of the germ theory, substantiated by his
numerous experiments and demonstrations, that were the principle factor in
convincing the scientific community that the theory was correct.
If diseases were caused by germs, it
seemed logical that by preventing harmful germs from entering the human body,
diseases might be avoided. Pasteur therefore stressed the importance of
antiseptic methods for physicians, and he was a major influence on Joseph Lister who introduced antiseptic methods
into surgical practice.
Harmful bacteria can enter the human
body through food and beverages. Pasteur developed a technique (called pasteurization) for destroying microorganisms in beverages. That technique, where practiced, has all but eradicated
contaminated milk as a source of infection.
When he was in his
mid-fifties, Pasteur turned his attention to the study of anthrax, a serious infectious
disease which attacks cattle and many
other animals, including human beings. Pasteur was able to show that a
particular species of bacterium was responsible for the disease. Of far greater
importance, however, was his development of a technique for producing a
weakened strain of the anthrax bacillus.
Injected into cattle, this weakened strain produced a mild form of the
disease, which was not fatal but which
enabled the cattle to develop an immunity to the normal form of the disease. Pasteur's
public demonstration of the effectiveness of his technique in immunizing
cattle against anthrax aroused great excitement. It was soon realized that his
general method might be applied to the prevention of many other communicable diseases.
Pasteur himself, in
his most renowned single achievement, developed a technique for inoculating
people against the dreaded disease of rabies. Other scientists, applying
Pasteur's basic ideas, have since developed
vaccines against many other serious diseases, such as epidemic typhus and
poliomyelitis.
Pasteur in his laboratory.
Pasteur, who was
an unusually hard worker, has a variety of
lesser but still useful achievements to his credit. It was his experiments,
more than any others, which convincingly demonstrated that microorganisms do
not arise through spontaneous generation. Pasteur also discovered the
phenomenon of
anaerobiosis; i.e., that certain microorganisms can live in the
absence of any air or free oxygen. Pasteur's work on diseases of silkworms has
been of great commercial value. Among his other achievements was the
development of a vaccine for the prevention
of chicken cholera, a disease that attacks fowl. Pasteur died in 1895,
near Paris.
A comparison is often made between
Pasteur and Edward Jenner, the English physician who developed a vaccine
against smallpox. Though Jenner's work was done more than eighty years before
Pasteur's, I consider Jenner much less important because his method of
immunization worked for only one disease, whereas Pasteur's methods could
be-and have been-applied to the prevention of a large number of diseases.
Since the
mid-nineteenth century, life expectancies in much
of the world have roughly doubled. This enormous increase in human life spans has probably had a greater effect
on the lives of individual human
beings than has any other development in the entire history of the human
race. In effect, modern science and medicine have presented each of us now
living with virtually a second lifetime. If this increase in longevity could be
solely attributed to the work of Pasteur, I would have had no hesitation at
all in placing him first in this book. Nevertheless, Pasteur's contributions are so fundamental that there is no
question that he deserves the largest share of the credit for the
decline in death rates that has occurred in the last century, and that he is
there-fore assigned a high place on this list.
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