Emil Heinrich du Bois-Reymond (7 November 1818 – 26 December 1896) was a German physiologist, the co-discoverer of nerve action potential, and the developer of experimental electrophysiology.

In 1840 Müller made du Bois-Reymond his assistant in physiology, and as the beginning of an inquiry gave him a copy of the essay which the Italian physicist Carlo Matteucci had just published on the electric phenomena of animals.

Du Bois-Reymond built up this branch of science, by inventing or improving methods, by devising new instruments of observation, or by adapting old ones.

[citation needed] His theory was soon criticized by several contemporary physiologists, such as Ludimar Hermann, who maintained that intact living tissue such as muscle does not generate electric currents unless it has suffered injury.

[11] The subsequent controversy was ultimately resolved in 1902 by du Bois-Reymond's student Julius Bernstein, who incorporated parts of both theories into an ionic model of action potential.

Following France's declaration of war on Prussia on 3 August 1870, du Bois-Reymond proclaimed that "the University of Berlin, quartered opposite the King's palace, is, by the deed of its foundation, the intellectual bodyguard (geistige Leibregiment) of the House of Hohenzollern.

"[16][17] But by the time of France's surrender on 26 January 1871 du Bois-Reymond had come to regret his words, lamenting the "national hatred of two embittered peoples.

[21]One historiographer described du Bois-Reymond's attention to the history of science as "the first and indeed the most decisive attack on established historical scholarship" in the 19th century.

[23] He expounded the theory in popular classes at the University of Berlin, in itinerant lectures in the Ruhr and the Rhineland, and in formal addresses translated and reprinted across Europe and North America.

Unlike his rival Ernst Haeckel, du Bois-Reymond espoused a mechanistic interpretation of natural selection that anticipated modern views.