Who Dis cov ered It? Anton van Leeuwenhoek Why Is This One of the 100 Great est?

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Bac te ria
Bac te ria
BACTERIA
Year of Dis cov ery: 1680
What Is It? Mi cro scopic or gan isms ex ist that can not be seen by the hu man
eye.
Who Dis cov ered It? Anton van Leeuwenhoek
Why Is This One of the 100 Great est?
Why Is This One of the 100 Great est?
Just as Ga li leo used his tele scope to open the hu man ho ri zon to the plan ets and stars of
space, so van Leeuwenhoek used his mi cro scope to open hu man aware ness to the mi cro -
scopic world that was in vis i bly small and that no one had even dreamed ex isted. He dis cov -
ered pro to zoa, bac te ria, blood cells, sperm, and cap il lar ies. His work founded the sci ence of
mi cro bi ol ogy and opened tis sue stud ies and plant stud ies to the mi cro scopic world. He
com pleted hu man un der stand ing of the circulatory system.
How Was It Dis cov ered?
How Was It Dis cov ered?
Anton van Leeuwenhoek was born in 1632 in Delft, Hol land. With no ad vanced
school ing, he was ap pren ticed as a cloth mer chant and as sumed that buy ing and sell ing
cloth would be his career.
But van Leeuwenhoek was cu ri ous about the world and in ter ested in math e mat ics.
Com pletely self-taught, he learned enough math to moon light as a sur veyor and read what
he could about the nat u ral world around him. He never learned any lan guage other than
Dutch, so he was never able to read any of the sci en tific pa pers and re search (all writ ten in
Latin or French).
Mi cro scopes ex isted in Hol land by 1620. Chris tian Huygens and Rob ert Hooke were
the first two sci en tists to make sci en tific use of mi cro scopes. Both de signed and built
two-lens mi cro scopes (two ground glass lenses in side a thin metal barrel).
In 1657 van Leeuwenhoek looked through his first mi cro scope and was fas ci nated. He
tried a two-lens mi cro scope, but was dis ap pointed by its dis tor tion and low res o lu tion.
When he built his first mi cro scope, he used a highly curved sin gle lens to gain greater
magnification.
By 1673 van Leeuwenhoek had built a 270-power mi cro scope that was able to see ob -
jects only one-one-mil lionth of a me ter in length. Van Leeuwenhoek re mained very se cre -
tive about his work and never al lowed oth ers to see his mi cro scopes or setup.
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Van Leeuwenhoek started his mi cro scopic stud ies with ob jects he could mount on the
point of a pin—a bee’s mouth parts, fleas, hu man hairs, etc. He de scribed and drew what he
saw in pre cise de tail. By 1674 he had de vel oped the abil ity to fo cus on a flat dish and turned
his at ten tion to liq uids—wa ter drops, blood cells, etc.
Those 1674 stud ies were where he made his great dis cov ery. He dis cov ered a host of
mi cro scopic pro to zoa (bac te ria) in ev ery wa ter drop. He had dis cov ered mi cro scopic life,
in vis i ble to the human eye.
Van Leeuwenhoek ex panded his search for these unseeably small crea tures and found
them ev ery where: on hu man eye lashes, on fleas, in dust, and on skin. He drew and de -
scribed these tiny crea tures with ex cel lent, pre cise drawings.
Each draw ing of ten took days to com plete. As an am a teur, Van Leeuwenhoek had to
work at his sci ence in the eve nings and early morn ing hours when not at work. Em bar rassed 
by his lack of lan guage skills and by his poor spell ing (even in Dutch), van Leeuwenhoek
felt hes i tant to pub lish any ar ti cles about his won drous findings.
Be gin ning in 1676, he agreed to send let ters and draw ings to the Royal So ci ety of Lon -
don. They had them trans lated into Eng lish. That ex ten sive col lec tion of let ters (writ ten and
col lected over many de cades) formed the first and best map of the mi cro scopic world. What
van Leeuwenhoek ob served shat tered many sci en tific be liefs of the day and put him
de cades—if not cen tu ries—ahead of other re search ers.
He was the first to claim that bac te ria cause in fec tion and dis ease. (No one else be -
lieved it un til Pas teur proved it in 1856.) Van Leeuwenhoek saw that vin e gar killed bac te ria
and said that it would clean wounds. Again, it was two cen tu ries be fore his be lief be came
stan dard med i cal practice.
It was also 200 years be fore any one built a better mi cro scope. But with his mar vel ous
mi cro scope, van Leeuwenhoek dis cov ered the crit i cally im por tant mi cro scopic world.