Emil Heinrich du Bois-Reymond (1818-1896), German physiologist. Du Bois-Reymond was born in Berlin, and was educated there and at Neuchatel. At university he studied various subjects, eventually settling on medicine and the tutelage of Johannes Muller. Having seen a copy of Matteucci?s notes on electric phenomenal in animals, Du Bois-Reymond published a graduation thesis on electric fishes. Through experiment he discovered the cell action potential (or nerve impulse), a transient change in voltage across a membrane seen in cells such as neurons. In 1858 Du Bois-Reymond succeeded Muller as professor of physiology at Berlin, a post he held until his death.