Certain metallic poisons give rise to pigmentation of the tissues, e.g.
A tendency to pigmentation also develops in certain tissues of the body, such as the nerve and muscle cells.
In hepatogenous pigmentation (icterus or jaundice) we have the iron-free pigment modified and transformed by the action of the liver cells into bile pigment (bilirubin).
In regard to physical features they present at the present time very many varieties both of stature and of pigmentation, though on the whole they are probably the tallest and fairest of European peoples.
The individuals in which this diminished pigmentation is found are for the most part those living in caves, and it is probable that their condition is not truly albinotic, but only temporary and due to the absence of the stimulus of light.
Pigmentation of the skin may occur in the later stages.
In extraneous pigmentation we have coloured substances either in a solid or fluid state, gaining entrance into the organism and accumulating in certain tissues.
In some cases, as in all the varying hares, in addition to the eyes retaining their normal pigmentation, areas similar in extent and situation to those on the Himalayan rabbits also retain their pigmentation; and in the ptarmigan there is a black band on each side of the head stretching forwards and backwards from the eyeball, and the outer tail feathers are black.
A moment's consideration, however, will show that, while an albino may be an individual in which one or more of the complementary bodies of pigmentation are absent, a pigmented animal is something more than an individual which carries all the factors necessary for the development of colour.
These are the atrial coelomic funnels or brown funnels, so called on account of the characteristic pigmentation of their walls.
By pigmentation is here meant all those factors which go to its production.