Marshall Hall, 1790–1857, English physician and physiologist, M.D. Univ. of Edinburgh, 1812. He practiced medicine in Nottingham and in London. He opposed bloodletting and devised a method of artificial respiration named for him. As a result of his experiments with animals he advanced (1833) the theory of reflex action in a paper before the Royal Society; despite some opposition the theory was later universally accepted. His works also include The Diagnosis of Diseases (1817) and Memoirs on the Nervous System (1837).