The Science Book

56

MICROSCOPIC

OBSERVATIONS

OF ANIMALCULES

ANTONIE VAN LEEUWENHOEK (1632–1723)

A

ntonie van Leeuwenhoek

rarely ventured far from his

home above a cloth store

in Delft in the Netherlands. But

working on his own in his back

room, he discovered an entirely

new world—the world of previously

unseen microscopic life, including

human sperm, blood cells, and,

most dramatically of all, bacteria.

Before the 17th century, no one

suspected there was life too small

to see with the naked eye. Fleas

were thought to be the smallest

possible form of life. Then, in about

1600, the microscope was invented

by Dutch eyeglasses makers who

put two glass lenses together to

boost their magnification (p.54).

In 1665, English scientist Robert

Hooke made the first drawing of

tiny living cells that he had seen in

a slice of cork through a microscope.

It never occurred to Hooke or

any other microscopist of the time

to look for life anywhere they could

not already see it with their own

eyes. Van Leeuwenhoek, by

contrast, turned his lenses on

places where there appeared to be

no life at all, particularly in liquids.

He studied raindrops, tooth plaque,

dung, sperm, blood, and much

more. It was here, in these

When van Leeuwenhoek’s

drawings of human sperm were first

published in 1719, many people did

not accept that such tiny swimming

“animalcules” could exist in semen.

IN CONTEXT

BRANCH

Biology

BEFORE

2000 BCE Chinese scientists

make a water microscope with

a glass lens and a water-filled

tube to see very small things.

1267 English philosopher

Roger Bacon suggests the

idea of the telescope and

the microscope.

c.1600 The microscope is

invented in the Netherlands.

1665 Robert Hooke observes

living cells and publishes

Micrographia.

AFTER

1841 Swiss anatomist

Albert von Kölliker finds that

each sperm and egg is a cell

with a nucleus.

1951 German physicist Erwin

Wilhelm Müller invents the

field ion microscope and sees

atoms for the first time.