Har·vey \ˈhär-vē\ , William (1578–1657), British physician and physiologist. Considered one of the greatest physiologists of all time, Harvey wrote a treatise on the circulation of blood that is perhaps the foremost treatise in the history of physiology. First presented in lecture form in 1616, it was published in 1628. In this treatise, based upon the detailed observations of the anatomy and physiology of eighty species of animals and the dissection of cadavers, Harvey expounded his argument for the circulation of blood and the function of the heart as a pump. In 1651 he published a treatise on embryology in which he formulated the basic principles of epigenesis. One of the foremost physicians in England, he was physician to James I and Charles I.