American neurologist and physiologist who was the first to use X rays in physiological studies. These led to his publication of The Mechanical Factors of Digestion (1911). His investigations on hemorrhagic and traumatic shock during World War I were summarized in Traumatic Shock (1923). He worked on methods of blood storage and in 1931 discovered sympathin, an adrenaline-like substance that is liberated at the tips of certain nerve cells.

Cannon's work on the emergency functions of the sympathetic nervous system and on homeostasis are reported in Bodily Changes in Pain, Hunger, Fear and Rage (1915) and in The Wisdom of the Body (1932). His contributions to the knowledge of the chemical mediation of nerve impulses were published (with A. Rosenblueth) in Autonomic Neuro-effector Systems (1937) and The Supersensitivity of Denervated Structures (1949). He was graduated in medicine from Harvard (1900) and taught there from 1899 to 1942.