On Sept. 17, 1683, Antonie van Leeuwenhoek of the Netherlands documented his observations of microorganisms, including bacteria – which he called “little animalcules”—that he found in a sample of plaque from his own teeth in a report to the Royal Society of London.
Using his own handmade microscopes, the Dutchman made a number of key scientific discoveries throughout his career, including bacteria, infusoria, micro-algae, spermatozoa, and red blood cells.
Van Leeuwenhoek was something of an academic late bloomer. He never attended a university and through his 20s and 30s worked as a draper, then as a land surveyor. He started his career as a research scientist in microbiology at the age of 38.
He was also an innovator in public science education, writing a book for everyday readers about his discoveries, and another book describing the development of a flea across its lifecycle (micro-biology had a heavy emphasis on flea research at that time). For more on Van Leeuwenhoek check out the articles here and here.
