born Oct. 19, 1871, Prairie du Chien, Wis., U.S.
died Oct. 1, 1945, Franklin, N.H.
U.S. neurologist and physiologist.
He was the first to use X rays in physiological studies. He also investigated hemorrhagic and traumatic shock during World War I and worked on methods of blood storage. He researched the emergency functions of the sympathetic nervous system and homeostasis and sympathin, an epinephrine-like substance released by certain neurons. With Philip Bard he developed the Cannon-Bard theory, which proposed that emotional and physiological responses to external situations arise simultaneously and that both prepare the body to deal with the situation.