1640-1704

French physician who was one of the first to attempt therapeutic transfusions of blood from animals to humans. In 1667, with the help of Paul Emmerez, a surgeon and anatomist, Denis injected blood from a lamb into a fifteen-year-old boy who had suffered from a fever. After several apparently successful experiments, a patient died after two injections of calf's blood. Although Denis was not found guilty of malpractice, Denis and Emmerez discontinued their experiments.