October 24 — Antoni von Leeuwenhoek born (1632)

Antoni von Leeuwenhoek, the Dutch scientist known as the “father of microbiology” was born on October 24, 1632.  Leeuwenhoek was the first person to identify the small “animalcules” that we now know as bacteria and other forms of microscopic life.

Leeuwenhoek was anything but a classical biologist.  Born in Delft, Holland, to working class parents, he had little formal education.  He became an apprentice to a fabric-maker in Amsterdam and returned later to Delft to take up the textile trade.  Textile makers and buyers often used magnifying glasses to inspect their wares, and Leeuwenhoek acquired his first lens in 1653.  Soon after, he began to grind his own lenses.

He was quite talented at grinding lenses and polishing glass, and, accompanied by a naturally acute sense of vision, he began making his own versions of microscopes (he is sometimes credited with inventing the microscope, but that isn’t true).  Over his lifetime, he made more than 500 microscopes.  He made tiny pin-hole lenses, which he imbedded between sheets of copper.  Behind the lens, he fashioned a tiny pin that could hold specimens and a pair of screws that moved the specimen into focus.  While the early compound microscopes of the day could achieve only about 20-power magnification, Leeuwenhoek’s single-lens devices could produce 200-power magnification.  His skill at glass-making, lighting and delicate movements made him able to use the devices much more effectively than others.

Then the fun started! He began to examine unlikely bits of the biosphere—water drops from a lake, deposits scraped from between his teeth, blood.  Then he went on to virtually anything he could get behind a lens.  He found an abundance of simple living organisms and other biological structures, like blood cells and tiny hairs on microorganisms that we now call cilia.  He demonstrated how blood flows through blood vessels.  He was the first to describe bacteria, considered his most important accomplishment.  But he also discovered nematodes and rotifers, and described green algae Spirogyra and Vorticella.

From 1673 on, he wrote regular letters to the Royal Society of London.  Although he wrote in his native Dutch and had no academic credentials, the society translated his letters and published them.  Slowly he gained credibility as his discoveries were confirmed one after the other.  He was awarded membership in the Royal Society in 1680 and continued writing about his observations until the very end of his life in 1723.

Although naturalists tend to focus on big things—the so-called “charismatic megafauna”—we now know that the actions of microorganisms are essential to the ecological processes that support ecosystems and civilizations.  Water is cleaned, soil is created, materials 32are cycled, all as part of the life-cycles of microorganisms.  For that reason, Antoni von Leeuwenhoek, who first opened our eyes to the lives of tiny things, deserves a place in the annals of great conservationists!


Coghlan, Andy.  2015.  Leeuwenhoek’s ‘animalcules’, just as he saw them 340 years ago.  New Scientist Daily News, 20 May 2015.  Available at:  https://www.newscientist.com/article/dn27563-leeuwenhoeks-animalcules-just-as-he-saw-them-340-years-ago/.  Accessed October 24, 2017.

University of California Museum of Paleontology.  Antony van Leeuwenhoek (1632-1723).  Available at:  http://www.ucmp.berkeley.edu/history/leeuwenhoek.html.  Accessed October 24, 2017.