Anton van Leeuwenhoek (1632-1723) was a Dutch scientist who discovered bacteria, or "little beasties" as he called them. Interested in making microscopes and then studying everything he could find, Leeuwenhoek happened to observe a drop of rain water taken from a barrel beside his house. He discovered that it was filled with "wretched beasties moving about very nimbly." He wrote extensively and drew pictures of what he saw, and although he did not realize that the bacteria he was studying caused disease, his work soon enabled scientists to make that discovery.
An uneducated man who never learned Latin, then the language of scholars, Leeuwenhoek lived his entire life in Delft, Holland. As a boy he was trained to clerk in a dry goods store, and part of his job was to examine cloth beneath a magnifying glass, but whenever possible he would examine other things beneath his glass. He later owned his own dry goods shop, but in his spare time he pursued his great interest in close examination of the things about him. He learned to grind lenses and build microscopes of his own. Some of the 247 instruments he built magnified the size of an object as much as 270 times.
When Leeuwenhoek was about forty years old and a widower with a grown family, he decided to spend the remainder of his life doing what he wanted. He sold his shop and devoted all of his time to making observations through his microscopes and building better and more powerful microscopes. He studied bacteria, yeast cells, and blood corpuscles. He also drew pictures of muscle fibers and described how the blood circulated in the body.
When he passed away at the age of ninety-two, Leeuwenhoek was famous, yet possibly his greatest contribution to science was that he had prepared the way for Louis Pasteur to open the whole new field of bacteriology.
