Emil Heinrich du Bois-Reymond (7 November 181826 December 1896) was a German physician and physiologist, the co-discoverer of nerve action potential, and the developer of experimental electrophysiology. Life Du Bois-Reymond was born in Berlin and spent his life there. His younger brother was the mathematician Paul du Bois-Reymond (1831–1889). His father was a poor immigrant from Neuchâtel, and his mother was a Berliner of prominent Huguenot origin. Educated first at the French College in Berlin, du Bois-Reymond enrolled in the University of Berlin in 1838. He seems to have been uncertain at first as to the topic of his studies, for he was a student of the renowned ecclesiastical historian August Neander, and dallied with geology and physics, but eventually began to study medicine with such zeal and success as to attract the notice of Johannes Peter Müller (1801–1858), a well-known professor of anatomy and physiology. Müller's earlier studies had been distinctly physiological, but his preferences caused him later to study comparative anatomy. He had, about the time when the young du Bois-Reymond came to his lectures, published his Elements of Physiology, in which the following statement occurs: "Though there appears to be something in the phenomena of living beings which cannot be explained by ordinary mechanical, physical or chemical laws, much may be so explained, and we may without fear push these explanations as far as we can, so long as we keep to the solid ground of observation and experiment." During 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 Carlo Matteucci had just published on the electric phenomena of animals. This determined the work of du Bois-Reymond's life. He chose as the subject of his graduation thesis Electric fishes, and so commenced a long series of investigations on bioelectricity. The results of these inquiries were made known partly in papers communicated to scientific journals, but also and chiefly by his work Investigations of Animal Electricity, the first part of which was published in 1848, the last in 1884. In 1852 while living alone and unable to get a professorship he traveled to England and met a distant cousin named Jeannette Claude whom he courted and married in 1853. Concerning his religious opinions, du Bois-Reymond was an atheist or at best agnostic. Works Investigations of Animal Electricity may be seen in