This middle portion is bare on its convex surface, which is smooth, whitish behind where this colour forms a kind of half moon, reddish in the greater part of its extent, a colour which is foreign to it and which it derives from the subjacent texture. Upon the sides, the skin covers this surface a little, and terminates afterwards by continuing the concave and free edge of which we have spoken. The epidermis forms also in this place a small string which is continued on each side with that pointed out above; then it unites to the nail and adheres to its lateral edges with which it is identified. The concave surface of this middle portion is fixed in front by the epidermis, which, after having covered the extremity of the fingers, and having arrived at the place where the nail ceases to be free, is separated from the dermis, and adheres to the whole length of the nail in a curved line; then by mixing with it, it seems to form its internal lamina. The dermis on the contrary is continued on the convexity of the last phalanx, has there a remarkable consistence, a reddish appearance, and a texture like pulp and wholly different from what is observed elsewhere; more vessels run through it; there is no distinct space in it, and no elongation goes from it to the surface of the nail of which the epidermis forms a part. We do not see on this surface, as on those of the other parts of the epidermis, those threads, which are the remains of the broken exhalants and of which we have spoken; thus the sweat never passes through the nail. There is neither any oily oozing upon its surface; whence it follows that water is not formed into little drops on the exterior of its horny laminæ. Hence the nail is evidently insulated from all the other organs except the epidermis, with which it is continued on its concave face and especially on its posterior and lateral edges. Thus observe that when collections of pus or other affections have broken this continuity behind or on the sides, the whole of the nail, though unaffected in the middle falls off. The free or anterior portion of the nail is of a length which it is difficult to determine. I have never seen it allowed to take its natural growth. I have only observed that if it is permitted to grow to a considerable size, we see evidently that it has a greater thickness than the posterior and middle portion. In general, the thickness, resistance and hardness of the nail increase in a gradual manner from the posterior to the anterior part; we shall now examine to what this is owing. II. _Organization; Properties, &c._