Antony van Leeuwenhoek

Dutch naturalist 1632-1723

Antony van Leeuwenhoek is often credited with inventing the microscope. In actuality, Galileo, Robert Hooke, and Jan Swammerdam had built mi­croscopes before him; compound (double-lens) microscopes were invented nearly forty years before Leeuwenhoek was born. Those early microscopes, however, were relatively crude and could magnify only twenty to thirty times. This was enough for Galileo to recoil at how ugly he thought a flea was at such a scale, but it was Leeuwenhoek who first produced microscopes capable of seeing single cells, achieving useful magnifications up to two hun­dred times.

This important step forward was due to Leeuwenhoek’s extreme pa­tience and skill in grinding lenses, and to his insatiable curiosity, acute eye­sight, and keen observational skills. These personal qualities were more important than higher education or scientific expertise, for Leeuwenhoek was not a scientist and, indeed, had no university education. He neverthe­less became one of the most important figures in the history of biology.

Leeuwenhoek was a textile merchant and minor city official in his na­tive city of Delft, Holland. His original motive for designing a microscope was to examine the weave of fabrics more closely so he could judge their quality and set a fair price. His simple (single-lens) microscope consisted of a ground glass bead mounted over a hole in a rectangular brass plate, with a tiny clip for holding a specimen near the lens. The plate had to be held close to the eye, with good backlighting and great patience.

Intent on studying more than fabric, Leeuwenhoek examined pond wa­ter, tooth scrapings, animal tissues, and almost anything else he could lay hands on. He was the first to see protozoans, bacteria, sperm and blood cells, muscle striations, and blood capillaries. Leeuwenhoek was hesitant at first to communicate with scientists, who were more highly educated and some­what intimidating to him, but in 1673 he began corresponding with the Royal Society of London, describing his observations in such vivid prose that even twenty-first-century biologists can instantly recognize the organ­isms he had seen. To Leeuwenhoek, they were an esthetic delight; “little animals, very prettily a-swimming” was how he described bacteria from the mouths of men who had gone all their lives without cleaning their teeth.

Leeuwenhoek became famous for his reports and was elected to the Royal Academy in 1680. The cell theory—the idea, among other principles, that all living things are composed of cells—is probably the single most impor­tant principle in biology and medicine, and it all began with a modest Dutch cloth-seller.

References

Dobell, Clifford. Antony van Leeuwenhoek and His “Little Animals.” New York: Dover, 1960.

University of California at Berkeley. <www.ucmp.berkeley.edu/history/leeuwenhoek. html>.