while the most sandy escaped, and multiplied and replenished the earth with their own likes.' !

Thus, then, is explained the tawny colour of the larger animals that inhabit the desert, the stripes upon the tiger, which parallel with the vertical stems of bamboo, conceal him as he stealthily nears his prey, the brilliant green of tropical birds, the leaf-like form and colours of certain insects, the dried twig-like form of many caterpillars, the bark-like appearance of tree-frogs,

the harmony of the ptarmigan's summer plumage with the lichen-coloured stones on which it sits, the dusky colour of creatures that haunt the night, the bluish transparency of animals which live on the surface of the sea, the gravel-like colour of flat-fish that live at the bottom, and the gorgeous tints of those that swim among the coral reefs.

Among the secondary causes of modification of species among animals Darwin gives prominence to 'sexual selection,' or the struggle between males for the

6

P. 97; and cf. G. A.'s art. Mimicry,' Encycl. Brit. xvi. p. 341.

185

to rank

y signs hose of

ess the

ast of

on that than to xisting · primi

ese-a

always e than ience), small unable

, living nature, Finding

st arts, ce fire;

ht to it

ommon

d at the .h them

cretius, through of wild

of the

'ds with

What the

*9.

FIG. 74. Hemispheres of Brain of Chimpanzee and of Man, showing relative proportions of the parts.

(From Huxley's Man's Place in Nature, p. 101.)

a, posterior lobe; b, lateral ventricle; c, posterior cornu; x, hippocampus minor.

plains of Africa.' He describes the Fuegians, who rank amongst the lowest savages, as men 'whose very signs and expressions are less intelligible to us than those of the domesticated animals-men who do not possess the instinct of those animals, nor yet appear to boast of human reason, or at least of arts consequent on that reason.'1 Such races are much nearer to the ape than to the European, and it is from like accounts of existing savages that we may form some rough picture of ‘primitive' man.

Doubtless he was lower than the lowest of these—a powerful, cunning biped, with keen sense-organs (always sharper, in virtue of constant exercise, in the savage than in the civilised man, who supplements them by science), strong instincts, uncontrolled and fitful emotions, small faculty of wonder, and nascent reasoning power; unable to forecast to-morrow or to comprehend yesterday, living from hand to mouth on the wild products of nature, clothed in skin or bark, or daubed with clay, and finding shelter in trees and caves; ignorant of the simplest arts, save to chip a stone missile, and perhaps to produce fire; strong in his need of life and vague sense of right to it and to what he could get, but slowly impelled by common perils and passions to form ties, loose and haphazard at the outset, with his kind, the power of combination with them depending on sounds, signs, and gestures.

To quote the striking description from Lucretius, 'during the revolution of many lustres of the sun through heaven they led a life after the roving fashion of wild beasts. No one then was a sturdy guider of the bent plough, or knew how to labour in the fields with iron or plant in the ground young saplings. What the

1 Naturalist's Voyage round the World, p. 504, ed. 1879.

sun and rain had given, what the earth itself brought forth, was guerdon enough to content their hearts.'1

Such, in broad outline, was probably the general condition of the earliest known wanderers, the rude relics of whose presence are found associated with the bones of huge extinct mammals in old river beds and limestone caverns. As the successive deposits and their contents show, not till long ages had passed, bringing new and settled conditions, with knowledge of agriculture, metals, and other useful arts, do we find any marked progress among mankind. Even that progress, often checked in its zigzag course, and never an unmixed good, neither synonymous, as the many think, with a nation's imports and exports, has been confined to a minority of the species and to a narrow zone, while, compared to the antiquity of man, it is but as yesterday. The enterprise of the higher races has explored and utilised large tracts, and the pressure of population at the centres of civilisation has within quite recent periods vastly extended their periphery; but whole empires, like China, advancing to a certain stage, have, through isolation and the tyranny of custom or dread of change, stagnated, whilst the lowest races have remained unmodified, like the lowest organisms, and have more or less succumbed before the imported vices and the weapons of the white man. But the causes of arrest and of advance are alike complex: man, like every other living thing, is the creature of outward and inward circumstances, and many influences have worked in the shaping of his destiny. Certainly, extremes of climate have been fatal to advance beyond a given stage; it is in the temperate zones that the incentives exist to continuous and indefinite progress.

In reviewing the several operations by which species

De Rerum Naturâ, v. 933-938; and cf. Odyssey, ix. 106-115.