<P> Beginning with William Harvey's experiments on the circulation of blood, research into blood transfusion began in the 17th century, with successful experiments in transfusion between animals . However, successive attempts by physicians to transfuse animal blood into humans gave variable, often fatal, results . </P> <P> Pope Innocent VIII is sometimes said to have been given "the world's first blood transfusion" by his Jewish physician Giacomo di San Genesio, who had him drink (by mouth) the blood of three 10 - year - old boys . The boys subsequently died . The evidence for this story, however, is unreliable and may have been motivated by anti-semitism . </P> <P> Working at the Royal Society in the 1660s, the physician Richard Lower began examining the effects of changes in blood volume on circulatory function and developed methods for cross-circulatory study in animals, obviating clotting by closed arteriovenous connections . The new instruments he was able to devise enabled him to perform the first reliably documented successful transfusion of blood in front of his distinguished colleagues from the Royal Society . </P> <P> According to Lower's account, "...towards the end of February 1665 (I) selected one dog of medium size, opened its jugular vein, and drew off blood, until...its strength was nearly gone . Then, to make up for the great loss of this dog by the blood of a second, I introduced blood from the cervical artery of a fairly large mastiff, which had been fastened alongside the first, until this latter animal showed...it was overfilled...by the inflowing blood ." After he "sewed up the jugular veins," the animal recovered "with no sign of discomfort or of displeasure ." </P>

Where did the first blood transfusion take place