a French physician notable for having performed the first fully documented human blood transfusion, a xenotransfusion. He studied in Montpellier and was the personal physician to King Louis XIV. Denys administered the first fully documented human blood transfusion on June 15, 1667. He transfused about twelve ounces of sheep blood into a 15-year-old boy, who had been bled with leeches 20 times. The boy survived the transfusion. Denys performed another transfusion into a labourer, who also survived. Both instances were likely due to the small amount of blood that was actually transfused into these people, which allowed them to withstand the allergic reaction.
