The manufacture of overshoes and fishing boots is an analogous process, only the canvas base is more thickly coated with a highly pigmented rubber of low quality.
Some animals are wholly pigmented during the summer and autumn, but through the winter and spring they are in the condition of extreme partial albinism and become almost complete albinoes.
A popular conception exists that albinoes are less constitutionally strong than the pigmented individuals of the same species.
Among some flowering plants, however, the character has become one of specific rank, and among animals we have in the polar bear and the Greenland hare instances where partial albinism - for in them the eyes are black and other parts may be pigmented - has also become a specific character.
In the next stage of complication, seen in the supernumerary (seventh) ocellus of Charybdaea, the patch of pigmented and sensory epithelium is pushed in to form a little pit, in the T Aurelia aurita.
For it is to be expected a priori that, since albinoes were derived from pigmented progenitors and may at any time appear, side by side with pigmented brothers, in a litter from pigmented parents, they would be carrying the pattern determinants of some one or other of their pigmented ancestors.
Following up this line of investigation, Major Ronald Ross in 1895 found that if a mosquito sucked blood containing the parasites they soon began to throw out flagellae, which broke away and became free; and in 1897 he discovered peculiar pigmented cells, which afterwards turned out to be the parasites of aestivo-autumnal malaria in an early stage of development, within the stomachwall of mosquitoes which had been fed on malarial blood.
They are found one on each cephalic tentacle, and are simply minute open pits or depressions of the epidermis, the epidermic cells lining them being pigmented and connected with nerves (compare fig.
Miss Durham interprets her results as indicating that the skin of these pigmented animals normally secretes one or more tyrosinases.
Apteryx, which since Owen has generally been stated to be devoid of such an organ, likewise possesses a pecten; its base is, however, trumpet-shaped, covers almost the whole of the optic disk, and extends nearly to the lens in the shape of a thick, densely pigmented cone, without any plications, resembling in these respects the pecten of many Lacertilia (see G.