Early blood transfusion. Historical artwork of the English physiologist Richard Lower (1631-1691) transfusing blood into a man's arm from a lamb in 1667. The end of the tube used to puncture the blood vessels and transfer the blood is at top left. Lower first demonstrated the transfusion of blood from the artery of one dog to the vein of another in 1665. Later attempts by others to transfuse from animals to humans led to some deaths. Lower's Treatise on the Heart describes the heart as a muscular pump rather than an organ 'inflated by spirits'. He deduced that the bright red of arterial blood results from the mixing of dark venous blood with inspired air in the lungs.