Portrait of the German physiologist Emil Du Bois- Reymond (1818-1896), who is considered to be the father of scientific electrophysiology. He studied biology at the University of Berlin and for his graduation in 1843 he wrote a thesis on electric fishes. Du Bois-Reymond refined old instruments and invented new ones with which he was able to detect the passage of tiny electric currents in nerve and muscle fibres. He also suggested correctly that nerve impulses might be transmitted chemically.