Put thus, treatment of canker would at first sight appear to be easy. One would imagine that a simple and long-continued soaking of the entire foot in a strong enough antiseptic would be all that was needed. Clinical observation, however, shows that this is not so, and for this there must be reasons. The reasons are these: (1) Between us and the diseased layer upon which our attention must be directed is often a layer of normal horn, effectually protecting the tissues beneath from any dressing which we might consider beneficial. (2) Anything applied with the object of destroying septic material, but strong enough, or caustic enough, to injure the membrane upon which we are working, only makes the case worse. The superficial layer of the keratogenous membrane in which we have judged the disease to exist is, after all, but a delicate structure. When attacked by the application of too potent a drug its horn-secreting layer is easily destroyed, and thus, although we may succeed in establishing asepsis, we cannot expect at the point of injury a growth of horn. In its place we are confronted with large outgrowths of inflammatory fibrous tissue. (3) Shedding of the diseased horn and removal of the pressure exerted by the hoof faces us with hypertrophy of the exposed villi. The difficulty of meeting this with an adequate and evenly-distributed pressure is well enough known, and we find in that a further reason that the treatment of canker is superlatively difficult. (4) The material on which the animal has to stand is a distinct bar to the maintaining of a strict asepsis. When we have said this, it is easy to understand that canker is not to be successfully met with any so-called specific--that it makes but little difference what the application may be so long as it is antiseptic, and is used by a man thoroughly conversant with the difficulties he has to contend with, and with his mind firmly set upon surmounting them. With this point established, we will not devote more of our space to a consideration of the various dressings that have at different times been highly advocated in the treatment of the disease. It is interesting, however, to note that intensely irritating and caustic applications have been greatly in favour. Nitric acid, sulphuric acid (either alone or its action reduced by the addition of alcohol, oil, or turpentine), arsenic, butter of antimony, creasote, chromic acid, carbolic acid, arsenite of soda, and the actual cautery, have all been used. Without dwelling further on that, we may say at once that a correct treatment consists in (1) the removal of all horn overlying infected portions of the keratogenous membrane, (2) the application of an antiseptic not too powerfully caustic in its action, (3) frequent changes of the dressings in order to insure a maintenance of antisepsis, and (4) the application of an adequate pressure to the exposed soft structures. Thus combated, canker is curable.