The pigment is distributed throughout the skin, the cutaneous appendages and the iris.
In the skin, the distribution is not uniform, there being some regions of the body that have more, and some that have less; it is localised in the Malpighian mucous layer, i.e., the granular, germinative layer of the epidermis, which rests directly upon the papillæ of the derma or corium.
The derma, being abundantly supplied with blood-vessels, if seen by itself would appear red; but this color, due to the blood, is concealed to a greater or less extent by the epidermis, according as the latter contains more or less pigment. In the iris of the eye and in the piliferous appendages of the skin, among which we must, from the anthropological point of view, give chief place to the hair of the head, the pigment tends to accumulate, producing a constantly deeper shade.
Pigmentation constitutes an eminently descriptive characteristic, and consequently, in all attempts to determine it, must be subject to all manner of oscillations in judgment on the part of the observer; yet, because it also constitutes an ethnical characteristic, it deserves to be determined with precision. To this end we have in anthropology chromatic charts, corresponding not only to the various shades of the skin, but also to those of the piliferous appendages and of the iris. They consist of a graduated series of colour-tones extending over the entire possible range of the real colours of pigmentation in human beings; and every gradation in tone has a corresponding number. When we wish to use the charts practically, for the purpose of determining accurately the precise degree of pigmentation of a given person's hair, we need only to compare the tone of the hair with the colours of the chart, and, having identified the right one, to note the corresponding number. For instance, we may record: "Pigmentation of hair = 34 Br. (i.e., No. 34 in Broca's table). Or, again, if we are making a more complex study of all the children in a certain school, we may say: "The chestnut tones (35, 42, 43 Br.) constitute 87 per cent., the remaining percentage consists of the blond shades (36, 37, 46 Br.). And in the case of the skin and the iris the procedure is analogous. By this means the investigation is objective and accurate.
As a rule, the three pigmentations are determined in accordance with a reciprocal correspondence. The light colourings, as well as the dark, generally go together; i.e., a person having blond hair has also light eyes and a fair skin, and vice versa—in other words, the entire organism has either a greater or less accumulation of pigment in all its centres of pigmentation. Furthermore, these anthropological characteristics are accompanied by others of equal ethnical importance, such as the stature, the cephalic index, etc.; and all of them combine to determine an ethnic type in all its complex morphology.
In this, as in all other anthropological data, it is necessary to determine the limits between which it may oscillate. In the races of mankind, the colour of the skin ranges from a black brown to a gray brown, to brick red, to yellow, and to white; but among the population of Italy, and among Europeans in general (excepting certain localised groups, like the Lapps, etc.), the variation is confined within the limits of the so-called white tones, that is, from brunette to a sallow white, a rosy white, or a florid red, with each of which tints there are special corresponding grades of pigmentation for hair and eyes, and also, on broad, general lines, different ethnical characteristics oscillating within our normal limits of stature and cephalic index.
All of which may be summarised in the following table:
| Pigmentation | Stature | Cephalic index | ||
|---|---|---|---|---|
| Skin | Hair | Iris | ||
| Brunette | Black | Black | Medium or low | Dolichocephalic, |
| Yellow-white Pink-white | Light chestnut & blond. | Chestnut and blue. | Medium or high | Brachycephalic |
| Florid red | Red | Gray | (Outside of ethnical characteristics: the red colour of the hair is abnormal) | |
in which we have also included the abnormal colour of red hair, which plays a part in the actual colour scale of Italian pigmentation: not, however, as a racial characteristic, but rather as a deviation.