The ancient anatomists, it appears, recognised only two parts of the skin--the true skin, and the outer cuticle or epidermis. Malpighi discovered a third layer interposed between these, consisting of a sort of network, thence called _rete mucosum_, and believed to be the seat of colour in the negro. Albinus showed this to be a continuous layer, and not a network. Cruikshank discovered four layers--three membranes, and the fourth a layer of colour. Flourens, at a more recent period, made the number of intermediate layers five, four of which he showed to the French Academy; one of these, a mucous membrane underlying the pigment, is, according to this anatomist, a distinct organized body, existing only in men of dark colour, and entirely wanting in the white races, or else (which appears the more probable conjecture) maceration, and the ordinary process of examination, fail to detect it in the skin of white men. Lastly, the microscopical researches of Henle, Purkinje, and Schwann, go to prove that the outer integument does not consist of separate membranes, but is of a cellular structure, and that of these cells or "cytoblasts," there are three distinct kinds. We will not further analyse the different opinions as to the texture of the skin and position of the colouring material; it certainly throws no inconsiderable degree of doubt over certain classes of scientific investigation, to find each subsequent research entirely altering, and in some cases overturning, the previously received views.