John Berry Haycraft was a professor in physiology and carried out important medical research.
Haycraft was born in London, England in 1875 and received his medical education in Edinburgh. He worked for a time in Ludwig's laboratory in Leipzig.
In 1881 he was appointed chair of physiology at Masons College, Birmingham. He taught in Birmingham and attracted many students to the city. During his years in Birmingham and Edinburgh, Haycraft had been actively engaged in research and published papers on the coagulation of blood and in 1884, he discovered that the leech secreted a powerful anticoagulant, which he named hirudin, although it was not isolated until the 1950s, nor its structure fully determined until 1976.
Haycraft returned to London 1892 and was appointed a research scholar of the British Medical Association.
In 1893 he was appointed chair of physiology at University College, Cardiff where he worked until retirement in 1920. Haycraft died three years later.