DU BOIS, William Edward Burghardt, American educator : b. Great Barrington, Mass., 23 Feb. 1868, of negro descent. He was graduated at Fisk University 1888 and at Harvard 1890, subsequently studying at the University of Berlin. He has been a Fellow of Harvard, assistant in sociology at the University of Pennsylvania, professor of economics and history in Atlanta University, and since 1910 editor of The Crisis Magazine, New York He has published 'The Suppression of the African Slave Trade to the United States, 1638-1870' (1896) ; 'The Philadelphia Negro' (1899) ; 'Souls of Black Folk' (1903) ; 'John Brown' (1909) • 'Quest of the Silver Fleece' (1911) ; 'The Negro' (1915) ; editor of the Atlanta University 'Studies of the Negro Problem' (15 monographs, 1896-1915).
DU Emil, German physiologist : h. Berlin, 7 Nov. 1818; d. there, 26 Dec. 1896. He studied theology, geology and subsequently anatomy and physt ology at Berlin under Johann Midler. At the age of 22 he began those researches in animal electricity which occupied him for nearly 40 years. His first experiments were published in 'Untersuchungen iiber tierische Elektrizitat) (2 vols., 1848-49). His instruments were of his own invention, and with them he succeeded in demonstrating the electrical phenomena occur ring in muscular activity and in nervous activity, and established the law now bearing his name : that it is the variation of a current density and not the absolute value of current density at any given moment that acts as a stimulus to a muscle or motor nerve. He succeeded Muller as
professor of physiology in the University of Berlin in 1858. In 1867 he became permanent secretary of the Berlin Academy of Sciences and later was appointed imperial privy coun cillor. He also performed successful experi ments proving that muscular reaction at rest is neutral or slightly alkaline and acid after death, and that acid is produced in the act of contrac tion. His investigations include important research on the aperiodic state of the magnetic needle induced by high dampening powers. He also invented the method of reading messages over the Atlantic cable by watching the beam of light reflected from a mirror attached to the needle of a galvanometer. His reputation as a scientist is world-wide, and his researches form the basis of all further information on animal electricity% His other publications include 'fiber die Grenzen des Naturkennens) (6th ed., 1884) ; 'Gesammelte Abhandlungen zur all gemeinen Muskel-und Nervenphysik' (2 vols., 1875-77) ; 'Reden' (2 vols., 1886-87)i and 'Vorlesungen fiber die Physik des organischen Stoffwechsels' (1899). Consult Engelmann, (Gedfichtnisrede auf Emil Du Bois-Reymond' (Berlin 1898).