To vaccinate by puncture the lancet, or preferably the vaccinating lancet is generally employed. The device is charged with the virus, either by inserting it into a mature vesicle, when vaccinating from arm to arm, or by making use of preserved matter. The lancet is then introduced almost horizontally beneath the surface of the skin between the epidermis and the true skin where it is allowed to remain for a few seconds and then withdrawn in such a manner as to wipe off the virus from the point of the instrument. Withdrawal is generally followed by the appearance of a small drop of bloodIn this manner three or four punctures are made in each arm, which must be allowed to dry perfectly before the infant is dressed.