his patients on a strict diet for nine days, then inoculated with the smallest possible quantity of virus. The operation was not prohibited in England until the year 1840, although it involved much greater dangers than vaccination with cow-pox. The first inoculation with cow-pox seems to have been performed in 1774: by a farmer of Gloucester, named Jesty, though the pioneer in the extensive and general introduction of this method was Edward Jenner (1749-1823), of Berkeley, in Gloucestershire, who, therefore, is generally known as the "Father of Vaccination." The son of a clergyman, he began early the study of medicine and surgery, and during his apprenticeship received from a milkmaid information of the protective power of cow-pox against variola, as established by popular observation. (Sutton and others had proved that inoculation of _sheep_-pox was not efficient.) This communication so struck Jenner as a means of affording protection to the whole human race{227} that the subject never afterward left his mind. In 1770 he became a pupil of John Hunter, and when he communicated to him this idea the great surgeon said: "Do not think; investigate!" Accordingly he went to Berkeley and performed the little operation which has made him famous; and from 1778 until 1788 he communicated to Sir Everard Home such observations as he had made. But the first vaccination was performed in 1796, upon a boy, with matter from the hand of a maid who had contracted cow-pox in milking. [Illustration: 0247] In 1798 he published his memorable work, and afterward removed to London. He died full of fame and honor, in his native place, having-received rewards from the government amounting to one hundred and fifty thousand dollars, besides being made an honorary citizen of the city of London. The subsequent wide-spread practice of the method, and the formation of societies{228} for the promotion of vaccination are matters of recent history. The first vaccinations in the United States were performed by Doctor Waterhouse, Professor of Medicine in Harvard College, in 1800, upon four of his own children. The transmission of humanized virus through the system of the cow, and its subsequent employment in vaccination of human beings, was first practiced by Troja (1747-1827), of Naples, shortly after the introduction of human vaccination; but in 1810 this was prohibited in Italy. Compulsory vaccination was first extensively introduced in Germany in 1807; in England it was first legalized in 1827. The occasional temporary character of the protection thus afforded was first taught by Elsâsser in 1814. Schoenlein was the first to call attention to the distinction between variola and varioloid.