PROTECTIVE COLORATION AND RE SEMBLANCE. All organisms are beautifully adapted to the world around them, and this adaptation in a large proportion of animals ex tends to their colors. The adaptive coloration of animals, the harmony in tint and form with the trees or herbs on which they live, the moss-grown rocks among which they hide, or the sand over which they run. are a part of the general adaptation or harmony in nature. A desert ani mal is of a sandy complexion. a silkworm moth is brown, and the zebra, tiger, leopard, and butter flies are striped and barred or spotted, in response to the same agencies of light, heat or cold. moisture or dryness, that have had to do with the origin of species. Owing to this adaptive color ation, certain insects, frogs, reptiles. birds, and mammals are protected from the observation of their natural enemies.
In marine fishes the ground coloration is, according to Jordan. protective in its nature. The fish. especially if swimming near the bottom, is better protected if the olivaceous surface is marked by darker cross sheaths and blotches. These give the fish. he says, a closer resemblance to the weeds about it. or to the sand or rocks on which it lies. As a rule no fish which lies on the
bottom is ever uniformly colored. At a depth of from .50 to 150 fathoms in the tropics a large proportion are red of various shades. Several of the large groupers of the West Indies are rep resented by two color the shore form is olive and the deeper-water form is crim son. Deep-sea pikes are black or violet black, with no markings. Desert animals are gray or tawny or sandy; forest animals are green, ma rine animals olive or reddish, pelagic animals transparent, while the typical _kretic mammals and birds are white: the white color of their feathers or fur was undoubtedly primarily clue to the cold of the glacial period. The polar bear, hare, snowy owl. and Greenland falcon are white throughout the year. while the fox, lemming, American hare. ermine stoat. and ptarmigan change their summer dress of russet to white. There has been much discussion as to the causes of the white color of Arctic animals. It is by many attributed to cold. and this is evidently the primary cause. but to cold we should add dryness.
The blanching of the hairs is due to partial, not entire, depigmentation.