The superficial, or uppermost strata (_a_ and _b_), are the “Cuticle” or “false skin.” The outer layer (_a_) is hard, horny, and dry. It is composed of numerous fine scales laid upon one another, like the tiles upon the roof of a house, but adhering more closely together, so as to form one continuous sheet extending all over the body. The outermost of these scales are continually being shed, peeling off as scurf, or being rubbed off; and fresh ones are supplied by the next layer (_b_), which is a softer material and lies immediately upon the surface of the “cutis” or “true skin.” This softer layer (_b_) is often called the “_Rete Mucosum_.” It is made up of minute bags or bladders, named “cells” by anatomists, which grow and propagate upon the exterior of the true skin, being nourished by the blood in the skin. Those which lie nearest the cutis are the youngest and the softest. Gradually they are pushed outwards by their successors or offspring; and, as they approach the surface, they become flatter and drier and more adherent to one another, and are finally converted into the thin scales of the cuticle. Thus, there is no real line of division between the cuticle and the rete mucosum; but the cells of the latter are gradually transformed into the scales of the former. The rete mucosum is thicker in the Negro than in the white man, and contributes somewhat to the softness of his skin. It contains also the colouring matter in the form of minute black particles diffused among its cells (fig. 72). These particles disappear, more or less, as the cells become changed into scales; hence the outer part of the cuticle of the Negro is not so dark as the rete mucosum, but, as it is transparent, or nearly so, it allows the dark colour of the rete to show through it. Persons commonly speak of the cuticle as if it were the whole thickness of the skin. Thus, when a blister has drawn, they say the _skin_ is raised; whereas it is only the _cuticle_. This is forced off from the skin by the fluid effused into its softer layer--i. e. into the rete--in consequence of the irritating influence of the blister.