measure re-established, the great object of the surgeon is fit to be accomplished. The question is, which of the teeth are to be interfered with? One is diseased or dead, and there can be no doubt that the diseased tooth should be removed. That which is unnaturally long, obviously indicates that its power of growth is retained; and though hypertrophy is an abnormal action, teeth are not parts liable to that species of affection. The one which by its growth indicates vitality, therefore displays no symptom of disease; but the tooth that is reduced to the level of the gums, tells us that its power of self-preservation has ceased, and that its vitality is gone. If that tooth be felt, it will, in the majority of instances, be found loose, and therefore it can be easily extracted: the operation, however, is not then ended. Should the affected organ have occupied the upper jaw, a quantity of pus may flow freely into the mouth on its extraction, but more frequently such will not be the case: nevertheless, the discharge from the nostril, (should the case have been of long standing,) together with the softened and swollen condition of the facial bones, may convince the attendant that matter is locked up in the maxillary sinuses. Some writers speak of the antrum as the part most seriously affected; but I cannot find any thing corresponding to the antrum in the horse's head. That animal has no development of this description, and therefore it only shows ignorance to operate with a special view to opening an imaginary cavity. The maxillary sinuses are spacious cells, and freely communicate with the frontal sinuses, which are also large. These facial sinuses have but a limited and kind of valvular opening into the nasal chambers, and if pus is allowed to remain within them there is little hope of cure: therefore a means must be found for its escape. To this end the finger is employed to probe the alveolar cavity, whence the tooth was taken, and it will probably prove to be of no great depth. An instrument constructed for the purpose is now used, and with it a hole is made through the walls of the alveolar, directly into the maxillary sinus--his knowledge of anatomy teaching the operator so to direct his hand that none of the important nerves and vessels, which ramify through the parts he is penetrating into, may be injured. On the withdrawal of the instrument, pus will mostly follow, but not gush forth as from an ordinary abscess. A dependent orifice has now been established, and if the case is not a severe one, that may be sufficient: if, however, the disease is aggravated, it will be necessary to trepline the frontal and perhaps the maxillary bone, leaving in each a free space, from which a circular piece has been removed. Through the superior opening, warm water is injected; but if the stench be very offensive, a weak solution of chloride of lime or of creosote may be employed, and must be daily repeated.