born Feb. 12, 1637, Amsterdam, Neth.
died Feb. 15, 1680, Amsterdam
Dutch naturalist.
An adept microscopist, in 1658 he became the first person to observe and describe red blood cells. In his General History of Insects he accurately described and illustrated the life histories and anatomy of many insect species and classified insects into four major divisions, three of which have been more or less retained in modern classification. He studied tadpole and adult frog anatomy and described the ovarian follicles of mammals. His improved techniques for injecting wax and dyes into cadavers had important consequences for the study of human anatomy. He showed that muscles alter in shape but not in size during contraction.