Antony van Leeuwenhoek, 1632–1723, was a Dutch student of natural history and maker of microscopes. As apprentice to a draper, he would use a variety of lenses to examine cloth. It was probably this that led to his interest in lens making.
He assembled over 247 microscopes, some of which magnified objects 270 times. With these microscopes he would examine everything. In the course of his examination he discovered the presence of “micro” organisms - organisms so tiny that they were invisible to the naked eye. But they were visible through his microscopes. He called these tiny living organisms “animalcules”. He first described bacteria and the protozoans. He also observed the red blood cells in his detailed study of blood circulation. He was elected to the Royal Society of England in recognition of his work.