*Care after Vaccination.*--As vaccination is a surgical procedure, it should be conducted aseptically with a sterile instrument on clean skin, and the wound should be guarded against extraneous infection. It is well therefore to put either a sterile gauze cover or a clean shield over the wound as soon as the virus has been sufficiently absorbed, and to leave the protection on until the natural crust has been formed,--_i.e._, for a few hours. If the guard could be kept in position without motion and also without injurious pressure, it might remain until the process ended with the formation of a scar and the exfoliation of the crust; but practically it is so certain that the guard will be moved that it is wise to remove it and to trust to the protection of a clean muslin or linen cloth attached to the loose sleeve or other undergarment. For a day or two at the time when the inflammation is at its height it may be well again to guard by a shield against injury from a blow or push, but the shield should always be regarded as itself a danger. If by any accident the vaccine pustule becomes infected, it should be treated like any other infected wound,--the crust removed, the ulcer cleansed with antiseptics and dressed surgically. The immunity given by the pock is not at all lessened by this treatment. *Normal Clinical Course.*--After primary vaccination in man there is a stage of incubation lasting for from forty-eight to seventy-two hours; a papule then develops, and by the end of the third or fourth day this has begun to show umbilication and a vesicular structure. When fully developed, about the sixth day after vaccination, the vesicle is distended and pearly in color. On the seventh or eighth day the areola develops,--_i.e._, the skin about the vesicle becomes hard, sensitive, and red, the redness extending a variable distance, not usually more than two inches from the edge of the vesicle. In the course of the next day or two the vesicle loses its pearly appearance and becomes opaque and often slightly yellow. With the development of the areola and of the pustule the adjacent lymph glands may swell and become somewhat painful; there may also be constitutional derangement,--some fever, pain, anorexia, restlessness, and more or less prostration; there is usually a moderate leucocytosis. About the eleventh or twelfth day the areola begins to fade, the constitutional symptoms to subside, and the pustule to dry up. A dark crust is formed which drops off usually between the eighteenth and twenty-fifth days, leaving a rosy depressed scar on which not infrequently a secondary scab is formed, to be shed a few days later. *Variations in the Clinical Course.*--The vesicles may appear on the second day, but it is more frequently delayed until the fourth, fifth, sixth, seventh, or even the eighth day, and cases have been observed in which the delay was even longer.