Sometime during the 1670s, a Dutch shopkeeper with no scientific training became the first person to see bacteria and other microorganisms that share our world. Though he wasn’t formally trained, Antoni van Leeuwenhoek, who sold fabric, ribbon, and buttons in Delft, a town in the Netherlands, was a curious man with a knack for making a lens that could magnify by about 270 times the microscopic world around us.
Born on October 24, 1632, van Leeuwenhoek is celebrated in Monday’s Google doodle as the father of microbiology. “More than being the first to see this unimagined world of ‘animalcules', he was the first even to think of looking – certainly, the first with the power to see,” wrote Nick Lane, a biochemist from University College London, in a journal of the Royal Society of London, the same body that received letters from van Leeuwenhoek himself. What van Leeuwenhoek called “animalcules” hundreds of years ago we know today as protists and bacteria.
Van Leeuwenhoek first saw them by peering at samples of water gathered from places like the canals near his house in Delft. What he discovered inside to his joyful astonishment were tiny, squirming creatures, “little eels, or worms, lying all huddled up together and wriggling … the whole water seemed to be alive with these multifarious animalcules,” he wrote.
The shopkeeper sent letters describing his discoveries to the prestigious Royal Society, apologizing for his simple language as he giddily painted a portrait of the mysterious and minuscule world he was discovering. In one of his most famous accounts, he describes the creatures inside the plaque he scraped from his own teeth:
“[T]here were many very little living animalcules, very prettily a-moving. The biggest sort … had a very strong and swift motion, and shot through the water (or spittle) like a pike does through the water. The second sort … oft-times spun round like a top … and these were far more in number.”
These and other plaque observations, which van Leeuwenhoek diagrammed, are among the first glimpses of living bacteria.
His discoveries at the time received mixed reactions from some skeptical scientists at the Royal Academy, but they did bring him some fame and the attention of notable figures. In 1698 he received an unexpected visitor, Russian czar Peter the Great, who sailed to the Netherlands to meet the Dutch merchant, as Robert Krulwich recounts for National Geographic.
The czar’s servants came to van Leeuwenhoek's house and said the monarch would have come himself, Mr. Krulwich writes, but worried that his appearance in the town would draw too much attention. Would van Leeuwenhoek grab some samples and join the czar aboard his royal ship? The Dutchman brought a live eel and a couple of his microscopes, and for two hours dazzled Peter the Great with a closeup view of blood flowing through the capillaries of the eel’s tail.