Over the generations the skin has been the site for immunization against smallpox. This method of immunization was described in a letter written by Lady Mary Montagu on April 1, 1717 in Adrianopole, Turkey: "The small-pox, so fatal, and so general amongst us, is here entirely harmless by the invention of ingrafting, which is the term they give it. . . The old woman comes with a nut-shell full of the matter of the best sort of small-pox . . . She immediately rips open (the skin) with a large needle . . . and puts into the vein as much venom as can lie upon the head of her needle, and after...