YOUMANS, William Jay (1838-1901). An American scientist, born at Milton, N. Y., brother of Edward Livingston Youmans (q.v.). He studied chemistry under his brother and at Columbia and Yale, then took a course in medicine at New York University, and in 1865 studied natural history under Huxley in London. On his return to the United States he settled at Winona, Minn., and practiced medicine for about three years. In 1872 he assisted his brother in establishing and subsequently was associated in editing the Popular Science Monthly. After his brother's death in 1887 he became its editor-in-chief. He edited Huxley's Lessons in Elementary Physiology, and wrote Pioneers of Science in America (1895).