James Sumner, son of a wealthy cotton manufacturer, learned early in life how to rise to a challenge. When he was 17, Sumner, accidentally shot by a hunting companion, had to have his left arm amputated. Although he had originally been left-handed, the young man retrained himself so well that he continued to excel in sports, becoming a champion tennis player, and a capable skier and mountain climber. Nevertheless, friends and teachers warned Sumner against trying to follow another of his dreams--becoming a chemist.

Ignoring the warnings, Sumner persisted. He studied chemistry at Harvard University, graduated in 1910 and taught for a while. Then, despite another warning from a college official, he returned to Harvard as a graduate student in biochemistry. After receiving his Ph.D. in 1914 he joined the faculty of Cornell Medical College, where he remained until his retirement in 1955.

Throughout his career, Sumner's chief interest was in...