Antoni van Leeuwenhoek

Although lacking basic scientific training, Antoni van Leeuwenhoek is credited with inventing the precursor to the modern microscope. Leeuwenhoek was the first to document the structure of red blood corpuscles and the nature of the circulatory system. In addition to describing animalcules (protozoans and bacteria), Leeuwenhoek also accurately described the life cycles of many types of insects.Culver Pictures 

During the same period, scientists began to understand some of the chemical processes in cells. In the 1920s, the ultra centrifuge was developed. The ultra centrifuge is an instrument that spins cells or other substances in test tubes at high speeds, which causes the heavier parts of the substance to fall to the bottom of the test tube. This instrument enabled scientists to separate the relatively abundant and heavy mitochondria from the rest of the cell and study their chemical reactions. By the late 1940s, scientists were able to explain the role of mitochondria in the cell. Using refined techniques with the ultra centrifuge, scientists subsequently isolated the smaller organelles and gained an understanding of their functions.

Credit : Microsoft® Encarta® Encyclopedia 2002. ©