Anton van Leeuwenhoek

1632-1723

Dutch Microscopist and Scientist

Known as the father of microbiology, Anton van Leeuwenhoek was a Dutch scientist who was the first to use a microscope to observe bacteria and protozoa (one-celled animals). His researches on lower animals refuted the then-held doctrine of spontaneous generation (the idea that living organisms could be created from inanimate matter), and his observations helped lay the foundations for the sciences of bacteriology and protozoology. Leeuwenhoek was an unlikely scientist. He had no formal training, but with his skill, his diligence, his endless curiosity, and an open mind free of the scientific dogma of his day, he succeeded in making some of the most important discoveries in the history of biology. He routinely shared his research and in the process opened up the entire world of microscopic life to the scientific community.

Leeuwenhoek was born in Delft, Holland, on October 24, 1632. His relatives were primarily tradesmen, so although he was educated as a child in the town of Warmond, he did not receive any further educational training. He lived with his uncle for a time at Benthuizen and apprenticed in a linen-draper's shop. Around 1654 he returned to Delft, where he spent the rest of his life. He set himself up in business as a fabric merchant, but he is also known to have worked as a surveyor, a wine assayer, and as a minor city official. In 1660 he obtained a position as chamberlain to the sheriffs of Delft. This secured his income and enabled him to devote much of his time to his hobby of grinding lenses and using them to study tiny objects. He seems to have been inspired to take up microscopy by having seen a copy of English physicist Robert Hooke's (1635-1703) illustrated book Micrographia (1665), which depicts Hooke's own observations with the microscope. While Leeuwenhoek's microscopes were simple in design, he possessed tremendous skill in grinding lenses. While he is often incorrectly credited with inventing the microscope, his lenses are generally regarded as having the best resolution of any microscopes in the era. Although Leeuwenhoek's studies lacked the organization of formal scientific research, his powers of careful observation enabled him to make discoveries of fundamental importance.

In 1674 Leeuwenhoek began to observe bacteria and protozoa, which he isolated from different sources and named animalcules. He accurately calculated the size of these specimens. He was the first to describe spermatozoa from insects, dogs, and humans. Leeuwenhoek also studied the structure of the optic lens, striations in muscles, the mouthparts of insects, and the fine structure of plants. He also discovered parthenogenesis (the reproduction of an egg unfertilized by a sperm) in aphids. In 1680 he gave detailed descriptions of yeast. He also demonstrated that spermatozoa were necessary for fertilization of the egg. Because of his hobby, a friend put him in touch with the Royal Society of England; Leeuwenhoek was elected as a fellow in 1680. Many of his discoveries were made public by the society.

Leeuwenhoek's microscopic research on the life histories of various low forms of animal life was in opposition to the doctrine that they could be produced by spontaneous generation. He showed that both grain weevils and fleas were produced not from grain or sand, as was the prevailing wisdom at that time, but that they were bred in the regular way of insects. He also demonstrated similar ideas in other animals. Leeuwenhoek became famous because of the dramatic nature of his discoveries. He gladly demonstrated his microscope for dignitaries the world over and continued to do so until his death in 1723.

JAMES J. HOFFMANN