Now, when any portion of these sensitive loops is injuriously irritated by pressure or friction, they sometimes push entirely through the cuticle, growing large and covering themselves with hard cuticular matter, thus forming the warts that appear on the hands and other parts of the body. Some corns, we believe, are produced in a similar way—a larger number of the papillæ projecting and being covered completely and thickly with epidermis, which, becoming dry and hard, still further pains the sore and sensitive papillæ as it is pressed upon by the boot. This kind of corn can be cured only as a wart is removed—by burning the papillæ, or, as they are called in the wart, the _roots_; thus changing the structure of the skin, or, in other words, making a scar. Ordinarily a hard corn commences at a point, or by the irritation of a small surface of the skin, or only a _few_ of the papillæ. From this point an increased supply of the cuticular matter is pushed out in every direction to protect them, growing harder as the process advances, and being more pressed against by the shoe, while the increasing external pressure incites the foot to push out a still larger corn. Thus it grows; and as the matter first thrown out is the first to become hardened, a point is formed, and the pressure forces it into the flesh, which is compelled to retire before it. The longer this is continued the larger the surface of skin that is made sore, the larger and more conical in shape the corn becomes, and the farther its point is forced into the flesh. This description is more especially true of the smaller corns; those which extend over a large surface being, probably, originated by a slighter irritation of a larger portion of the skin; hence they have less of a point and penetrate less deeply. Soft corns appear between the toes, and are soft for the reason that, so situated, they are kept moist by perspiration. Some of them are secretions of epidermis having no centre or point, but thrown out from the foot at the bottom and sides of the spade between the toes, and giving a sensation as of some foreign body, like a pea or a gravel stone, confined there. There may be others that are accompanied by projections of the papillæ. It is to be noticed that a corn is thus composed wholly of cuticular matter, and is entirely outside of the true skin.