XX EDWARD JENNER 1749-1823 _Edward Jenner, born May 17, 1749, at Berkeley, Gloucestershire, England, studied surgery under John Hunter at London, and returned to his native town to practise. Having learned, about 1796, that milk-maids who had caught the cow-pox were immune from small-pox, he began at once to make investigations and to conduct experiments. This led to his “Inquiry,” published in 1798, in which he made public his theory of vaccination. His discovery created widespread interest, but although the theory at once met with the most virulent criticism, vaccination was soon widely accepted. By 1801, ten thousand persons were vaccinated in England, and the beneficent results justified its wide adoption. He died of apoplexy, January 26, 1823._ THE THEORY OF VACCINATION[23] The deviation of Man from the state in which he was originally placed by Nature seems to have proved to him a prolific source of Diseases. From the love of splendour, from the indulgences of luxury, and from his fondness for amusement, he has familiarised himself with a great number of animals, which may not originally have been intended for his associates. The Wolf, disarmed of ferocity, is now pillowed in the lady’s lap. The Cat, the little Tyger of our island, whose natural home is the forest, is equally domesticated and caressed. The Cow, the Hog, the Sheep, and the Horse, are all, for a variety of purposes, brought under his care and dominion. There is a disease to which the Horse, from his state of domestication, is frequently subject. The Farriers have termed it the Grease. It is an inflammation and swelling in the heel, from which issues matter possessing properties of a very peculiar kind, which seems capable of generating a disease in the Human Body (after it has undergone the modification which I shall presently speak of), which bears so strong a resemblance to the Small-pox that I think it highly probable it may be the source of that disease.