Sir Alan Hodgkin (b.1914), British physiologist and Nobel Laureate. Hodgkin studied biology and chemistry at Cambridge. He became interested in the way that nerve fibres transmit signals, and performed experiments on single fibres from crabs and, later, from squid. Hodgkin discovered the potential difference between the core of a nerve axon and its membrane sheath, and that the potential is reversed as an impulse passes along the nerve. Hodgkin developed a detailed theory of the origin of this potential difference in terms of sodium and potassium ion distribution. Hodgkin shared the 1963 Nobel Prize for Physiology or Medicine for his work. Photographed in 1993.