Leeuwenhoek discovers microorganisms

Antonie van Leeuwenhoek, a Dutch cloth merchant in Delft with no university education, ground tiny lenses that magnified up to 270 times. In a letter to the Royal Society dated 9 October 1676, he described tiny living creatures he had seen in rainwater and in water steeped with pepper, which he called animalcules, and he later saw bacteria in the plaque from his own teeth, as well as sperm cells and red blood cells. Robert Hooke confirmed his observations. They were the first sightings of the microbial world, though germs were not linked to disease until the nineteenth century.

Open on the timeline