Caption

Walter Bradford Cannon (1871-1945), US physiologist. Cannon graduated from Harvard University in 1900. While still a student at Harvard, he had fed a cat a bismuth compound in a meal to make its digestive tract visible on an X-ray. This was the first use of a radio-opaque medium. Later Cannon worked on the effect of shock and emotions on the nervous system. He studied Bernard's idea of the necessity of a constant internal physiological environment and coined the term homeostasis to describe the processes by which this environment is maintained. This Harvard University photograph dates from 1896, Cannon's first year at Harvard.