Antonie van Leeuwenhoek |
On
September 17, 1683 Antonie van
Leeuwenhoek wrote a letter to the Royal
Society in London describing animalcules—tiny one celled animals invisible
to the naked eye now known as protozoa. In doing so he inadvertently founded a new branch of science—microbiology.
Leeuwenhoek was an unlikely
scientist. At the time most scientific investigation was
the sole providence of gentlemen who
had the education, leisure time for investigation, and the fortune
to support the cost of their work.
He was neither a gentleman or particularly well educated. He
came from a family of tradesmen or
what the English called skilled mechanics. His father
was a basket maker and his mother’s family were brewers. They were from Delft, a reasonably prosperous small
city in the Netherlands province
of South Holland.
As
a young man Leeuwenhoek became a draper. He also worked as a surveyor, wine assayer
and as a municipal official. His occupations made him comfortable, if not wealthy and he was a respected member of the
community. He was friends with and almost the exact
contemporary of Delft’s most famous
resident the painter Johannes
Vermeer and was an executor of his
estate when the master died in poverty in 1675.
His
commercial success allowed Leeuwenhoek the time to pursue his growing interest
in science. An avid reader, he had read Robert Hooke’s illustrated book Micrographia.
Hook was working with primitive compound
microscopes using two lenses. But the technology of he these devises were
primitive and could only magnify
objects 20 to 30 times. Around the mid
1660’s he began to grind lenses in
an attempt to create more effective instruments.
My
high school science text credited
Leeuwenhoek as the inventor of the microscope.
As you can see, he was not.
Compound microscopes had been around for nearly 40 years. His devices had single lenses, but the quality of the lenses was so high that he
was able to achieve documented magnification of over 200 times. And evidence from his detailed observations indicates that some of the devices that he
constructed may have neared a power of 500.
One of van Lueeuwenkhoek's deceptively simple but effective microscopes. |
Leeuwenhoek’s
breakthrough—and a closely guarded secret in his life
time—was not discovered until 1957 when scientists discovered that he used finely drawn thread of molten glass to
create perfect small spheres which
became his lenses. The small lens would
be set in a brass or silver plate in front of which would be a pointed rod on an adjustable screw which would hold the
object being studied. Leeuwenhoek,
working in the brightest natural light,
would hold the devise close to his eye.
Leeuwenhoek
constructed at least 500 different devices, only a handful of which still
survive. He often crafted new
microscopes specifically for the specimens he wished to examine.
He
made careful, extraordinarily detailed written observations of what he
saw. These observations are so clear
modern scientists can often identify the exact species of microbe he was
observing. Since his drawing skills were poor, he later also
hired a professional illustrator to
make drawings to be enclosed in his letters to the Royal Society and other
scientists.
His
correspondence with the Royal Society continued for more than 50 years through
his final illnesses. The Society
frequently published his findings translated from Dutch to English or Latin in the Philosophical Transactions of the Royal Society, the most
important scientific journal in the world at the time.
Illustrations of various spermatozoa sent to the Royal Society in London in 1679. |
Among his main discoveries were infusoria, the unicellular animals in pond water now mostly classified as protists;
bacteria from the human mouth; vacuoles, important structures
in the cells of plants, fungi, and some protia; spermatozoa;
the banded structure of mussel fiber; and the blood flow in capillaries.
In his later years Leeuwenhoek was famous.
He was visited by William of
Orange and other notables who he let make their own observations with his
equipment. He even presented a
microscope to Peter the Great of Russia when he was invited to visit the
Tsar’s ship.
Active
to the end, he died in Delft in 1723 at the age of 90.
In
1981 Leeuwenhoek’s original specimens,
sent to the Royal Society were discovered in a remarkable state of preservation along with many of his hand written notes in
Dutch.
His
life and work is a testament to the talent and persistence of a common craftsman.
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