Antonj van Leeuwenhoek (1632-1723)
A Dutch microscopist, studied the cellular structure of plants and animals, including bacteria, protozoans, and sperms. He also first published an account of such observations. He was probably the first to see bacteria (1676), and his descriptions were quite good considering the low magnifications (300 diameters) of the 247 microscopes that he constructed. Through his accurate accounts and observations he discovered free-living and parasitic protozoans (1674-1703) and is known as the father of protozoology.