One word of advice about corn-cutting. Most persons have some experience in this art, and some opportunity of practising it on themselves; and many pride themselves on their skill in it. The usual plan is to shave off layer after layer from the whole surface of the corn; and this, by lessening the projection of the corn, may give relief for a few days, though it does not always do that. Soon, however, the distress returns; and the area of the corn increases after each operation. Now, I would have you observe that it is at the _middle_ of the corn that the papillæ are most enlarged; and it is here that the formation of cuticle goes on most quickly, giving rise to the little white cone or cones often seen in a corn and sometimes wrongly called the roots. The proper mode is to confine the cutting to this part, and to remove as much of the thickened cuticle as you can from this spot, digging, as it were, a hole in the middle and leaving the circumference intact. The circumference, which is not usually tender, thus forms a wall round the excavated centre and defends it from pressure; and great relief is experienced. Further benefit will be found from covering the corn with some soft adhesive plaster; and you may sometimes, with advantage, lightly apply common caustic before putting on the plaster. If you follow these directions carefully you may be your own chiropodists, and almost defy your bootmakers. If, in cutting a corn, you go too deeply, you will wound the tops of the papillæ and cause some bleeding; this is not however usually followed by any ill consequences. _Nails._ Almost all vegetable as well as animal surfaces are covered with some kind of cuticle. It forms the smooth exterior of a leaf and the rind of an apple; and the soft down of a moth or a butterfly, the scales of fish, the feathers and claws of birds, the quills of the porcupine, the horns of oxen and the hoofs of the horse are examples of modifications of cuticle. NAILS and HAIR are also of this nature. They are both continuous with the cuticle, and peel off with it when it is, by any process, separated from the skin. Both are formed, like the cuticle, of compressed plates or scales matted together; and these are continually being shed or rubbed off on the one side, and supplied from the rete mucosum on the other. The rete mucosum, it should be stated, extends over the whole surface of the body. In most situations, as already mentioned, it is the medium from which the ordinary cuticle is produced; but on the upper part of the ends of the fingers and toes it is converted into nail, and in the hair follicles, as I will presently describe, it is transformed into hair. [Illustration: Figs. 75, 76, 77. Longitudinal sections of Nail.]