Louis Pasteur

PASTEUR, Louis (1822-95). The French chemist Louis Pasteur devoted his life to
solving practical problems of industry, agriculture, and medicine. His
discoveries have saved countless lives and created new wealth for the world.

Among his discoveries are the pasteurization process and ways of preventing
silkworm diseases, anthrax, chicken cholera, and rabies. *BR* Pasteur sought no
profits from his discoveries, and he supported his family on his professor\'s
salary or on a modest government allowance. In the laboratory he was a calm and
exact worker; but once sure of his findings, he vigorously defended them.

Pasteur was an ardent patriot, zealous in his ambition to make France great
through science. *BR* *BR* *BR* Scholar and Scientist*BR* Louis Pasteur was born
on Dec. 27, 1822, in Dôle, France. His father was a tanner. In 1827 the family
moved to nearby Arbois, where Louis went to school. He was a hard-working pupil
but not an especially brilliant one. *BR* When he was 17 he received a degree of
bachelor of letters at the Collège Royal de Besançon. For the next three years
he tutored younger students and prepared for the École Normale Supérieure, a
noted teacher-training college in Paris. As part of his studies he investigated
the crystallographic, chemical, and optical properties of various forms of
tartaric acid. His work laid the foundations for later study of the geometry of
chemical bonds. Pasteur\'s investigations soon brought him recognition and also
an appointment as assistant to a professor of chemistry. *BR* *BR* Pasteur
received a doctor of science degree in 1847 and was appointed professor of
chemistry at the University of Strasbourg. Here he met Marie Laurent, daughter
of the rector of the university. They were married in 1849. Pasteur\'s wife
shared his love for science. They had five children; three died in childhood.
*BR* *BR* *BR* *BR* Research in Fermentation and Souring*BR* In 1854 Pasteur
became professor of chemistry and dean of the school of science (Faculté des

Sciences) at the University of Lille. Hearing of Pasteur\'s ability, a local
distiller came to him for help in controlling the process of making alcohol by
fermenting beet sugar. Pasteur saw that fermentation was not a simple chemical
reaction but took place only in the presence of living organisms. He learned
that fermentation, putrefaction, infection, and souring are caused by germs, or
microbes. *BR* Pasteur published his first paper on the formation of lactic acid
and its function in souring milk in 1857. Further studies developed the valuable
technique of pasteurization (see Dairy Industry). The same year he was appointed
manager and director of scientific studies at his old school, the École Normale

Supérieure. During the next several years he extended his studies into the germ
theory. He spent much time proving to doubting scientists that germs do not
originate spontaneously in matter but enter from the outside. *BR* *BR* *BR*

Developing Cures for Agricultural Diseases*BR* In 1865 Pasteur was asked to help
the French silk industry, which was near ruin as a result of a mysterious
disease that attacked the silkworms. After intensive research, he discovered
that two diseases were involved, both caused by bacteria on the mulberry leaves
that provided food for the worms. The diseases were transmitted through the eggs
to the next generation of worms. Pasteur showed the silkworm breeders how to
identify healthy eggs under the microscope, how to destroy diseased eggs and
worms, and how to prevent formation of disease bacteria on the mulberry leaves.
*BR* At 45 Pasteur was struck by paralysis. For a time recovery was uncertain,
and he was confined to bed for months. The attack left its mark; for the rest of
his life, one foot dragged a little as he walked. *BR* *BR* In 1877 Pasteur
began to seek a cure for anthrax, a disease that killed cattle, sheep, and other
farm animals. He drew on research he was conducting on another animal disease,
chicken cholera. When he inoculated healthy chickens with weakened cultures of
the cholera microbes, the chickens suffered only a mild sickness and were
thereafter immune to the disease. Pasteur successfully applied this technique of
immunization to the prevention of anthrax. *BR* *BR* Many scientists challenged

Pasteur\'s anthrax prevention claims, and Pasteur agreed to a dramatic test.

Forty-eight sheep and a few cows and goats were gathered in a pasture near the
town of Melun. Half the animals were first immunized with cultures of weakened
anthrax microbes; then all were injected with strong cultures. *BR* *BR* Within
a few days, the untreated animals were dead; but the immunized animals showed no
effect of the disease. The test verified Pasteur\'s results beyond all doubt.