Antoni van Leeuwenhoek: First Person to Observe Bacteria

It's the birthday of Antoni van Leeuwenhoek, born in Delft, the Netherlands (1632). He perfected the microscope, and was the first person to observe bacteria. Leeuwenhoek was not a trained scientist; he studied to be a draper's assistant in Amsterdam. He became a draper and haberdasher, and eventually took an administrative job in the government. He devoted all of his spare time to his hobby, grinding glass lenses and making microscopes. Over his lifetime, he ground over 400 lenses, and he built many microscopes, using techniques that he kept secret. He used his own microscopes to become the first person to observe bacteria and protozoa, which he called "animalcules." He was also the first to see red blood cells. One of his most important contributions was his research on fleas. He was able to explain how insects breed, because he could, for the first time, see their tiny eggs. He argued against the popular theory of spontaneous generation, which said that the tiniest insects could be generated from thin air.
-Writer's Almanac