19 a 
DARWINISM 
CHAV. 
both inconsistent with any other theory than that the white 
colour of arctic animals has been acquired for concealment, 
and to that theory both afford a strong support. Here we 
have a striking example of the exception proving the rule. 
In the desert regions of the earth we find an even more 
general accordance of colour with surroundings. The lion, 
the camel, and all the desert antelopes have more or less the 
colour of the sand or rock among which they live. The 
Egyptian cat and the Pampas cat are sandy or earth coloured. 
The Australian kangaroos are of similar tints, and the 
original colour of the wild horse is supposed to have been 
sandy or clay coloured. Birds are equally well protected 
by assimilative hues; the larks, quails, goatsuckers, and 
grouse which abound in the North African and Asiatic deserts 
are all tinted or mottled so as closely to resemble the average 
colour of the soil in the districts they inhabit. Canon 
Tristram, who knows these regions and their natural history 
so well, says, in an often quoted passage: “ In the desert, 
where neither trees, brushwood, nor even undulations of 
the surface afford the slightest protection to its foes, a 
modification of colour which shall be assimilated to that of 
the surrounding country is absolutely necessary. Hence, 
without exception, the upper plumage of every bird, whether 
lark, chat, sylvain, or sand-grouse, and also the fur of all the 
smaller mammals, and the skin of all the snakes and lizards, 
is of one uniform isabelline or sand colour.” 
Passing on to the tropical regions, it is among their 
evergreen forests alone that we find whole groups of birds 
whose ground colour is green. Parrots are very generally 
green, and in the East we have an extensive group of green 
fruit-eating pigeons; while the barbets, bee-eaters, turacos, 
leaf-thrushes (Phyllornis), white-eyes (Zosterops), and many 
other groups, have so much green in their plumage as to tend 
greatly to their concealment among the dense foliage. Thero 
can be no doubt that these colours have been acquired as a 
protection, when we see that in all the temperate regions, 
where the leaves are deciduous, the ground colour of the 
great majority of birds, especially on the upper surface, is a 
rusty brown of various shades, well corresponding with the 
bark, withered leaves, ferns, and bare thickets among which 
