VI. _Colouring._ With all anthropologists I recognise the high value of the colour of the skin as a character. Nevertheless, its importance must not be exaggerated. We now know that it does not result from the existence or disappearance of special layers. Black or white, the skin always comprises a white _dermis_, penetrated by many capillaries, and an _epidermis_, more or less transparent and colourless. Between the two is placed the _mucous layer_, of which the _pigment_ alone in reality varies in quantity and colour according to the race. All the colours presented by the human skin have two common elements, the white of the dermis and the red of the blood. Moreover, each has its own proper element, resulting from the colourings of the pigment. The rays reflected from these different tissues combine into a resultant which produces the different tints and traverses the epidermis. This latter plays the part of roughened glass. The more delicate and the finer it is, the more perceptible is the colour of the subjacent parts. This arrangement explains why, among certain coloured races, for example, among the Sandwich Islanders, the upper classes, who do not live an exposed life, often exhibit the colour in a most pronounced form. Among them _sun-burning_ masks the colour of the pigment, as it masks with us the colour of the dermis and its vessels. From the preceding, we can also understand why the White alone can be said to _turn pale_ or to _blush_. The reason is, that in him the pigment allows the slightest differences in the afflux of blood to the dermis to be perceived. With the Negro as with us, the blood has its share in the colouring, the tint of which it deepens or modifies. When the blood is wanting, the Negro turns grey from the blending of the white of the dermis with the black of the pigment. It is well known that from the point of view of the colouring, human races can be divided into four principal groups: white, yellow, black, and red races. But we must guard against attaching an absolute sense to these expressions. Every grouping of races founded solely on colour would break close relations, and would lead to comparisons which would evidently be at variance with the sum of the remaining characters. Nevertheless, this systematic point of view brings to light some interesting general facts. The races of a white colour present sufficient homogeneity. From the sum of their characters, they belong almost exclusively to the type which borrows its name from this kind of colouring. It is, moreover, useless to insist upon the differences of tint which the latter exhibit, from the English or German woman of the upper classes to the Portuguese, and especially to the Arab. Nevertheless, in the northern regions and in Central Asia, some populations, the Tchukchees for example, _appear_ to unite with a white colour certain characters which connect them with the yellows.