As a matter of fact, in our own population of Latium the brunette type prevails over the blond by a percentage of 86 per cent.; and it may be that a blond Roman wet-nurse is a weakly creature, just as a Roman red wine is in all probability a white wine that has been coloured.
Pigmentation of the Iris.—In regard to the coloration of the eyes, a change often takes place at puberty which is the opposite to that already noted in regard to the hair: the eyes become more uniformly light; this happens in the majority of cases.
In the coloration of the eyes it is necessary to distinguish two factors, the uvea and the pigment.
The iris has a fundamental and uniform light colour (due to the uvea) which oscillates, according to the individual, between blue and greenish.
In this layer the pigment is deposited; it may be more or less intense in tone, shading from yellow to a dark maroon.
When the pigment is wanting or is very scant, the fundamental blue or greenish colour of the uvea is apparent.
In little children the pigment is distributed over the uvea in a manner by no means uniform, in little masses or spots that are usually of a mixed colour, so that the colour of the iris in infancy may be uncertain. At puberty a uniform distribution of the pigment already accumulated takes place; but rarely an intensification. Hence the colour becomes more decided, but not deeper, as Godin has recently succeeded in proving.
Pigmentation of the Skin.—In the colouring of the skin it is necessary to distinguish between that which is due to the blood and that which is due to the pigment.
The blood, whose colour shows transparently through the layers of the epidermis, produces the various pinkish tones.