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there is the original rock-pigeon, Columba livia ; on the other, its curiously modified and metamorphosed progeny--the pompous fan-tail with its exuberant plumage, the pouter with its inflated crop, the tumbler with its curious somersaults in the air, the carrier, the trumpeter, and a host besides. These differences are esteemed by our author as exceedingly significant; such indeed as might surprise an ornithologist, were the birds found in the wild state, into a coinage not only of specific but of generic names.10 Yet all this divergence consists with a common stock; all this can be brought about, within the limits of a species, by the cultivation of peculiarities, century after century, on the part of man.
11. Such the powers of artificial or human selection --of man as the educator of brute nature. But is this the only sort of selection by which animals can be modified ? Mr. Darwin contends that it is not. Advantageous peculiarities, he holds, are incessantly fostered by a process quite apart from human interference. cess is that of Natural Selection.
12. “ The Empire,” said the third Napoleon,“ is peace.” Nature, says Mr. Darwin, with at least equal accuracy, is War. The whole world of living things is one scene of struggle, one vast arena of truceless con
flict, an unremitting competition for food and for exist
And the race is to the swift, and the battle to the strong. The table of nature is crowded with guests; the superfluous multitudes must be thrust out and trampled down. In this state of things, every peculiarity, however slight, which gives an animal an advantage, however slight, over its rivals, will not only improve the fortunes of the individual, but probably travel down as an heirloom to its offspring. Let a peculiarity which chances also to be a prerogative emerge, and let members of the favoured race, at distant intervals but in definite directions, go on accumulating the like advantages; and we are assured that in such case, from mere “varieties," which our author contemplates as “incipient species,” there will issue fresh species, fully marked and developed, though not till after thousands or even myriads of generations. A peculiarity of this kind is deemed natural capital ; and money makes money, it is thought, in the world of nature as in the world of man. There may and must be an infinity of failures, but there will be happy hits notwithstanding. In this fashion, according to Mr. Darwin, all the higher tribes have fought their way up through the incalculable periods of
13. Incalculable periods. For, as the first factor in Mr. Darwin's scheme is War, so the second is Time. And certainly he is entitled to draw freely on the past. The sedimentary strata of Great Britain are nearly fourteen miles thick-Palæozoic = 10 miles, Secondary = 3 miles, Tertiary = 1 mile—and a typical diagram allowing for blanks and full development elsewhere, as in the Permian and later systems, of what is poorly represented in this island, would require for the whole series a scale enlarged by perhaps one-third. Now, what is a stratum ? It is the spoil won by the sea from the dry land. Mark how ceaselessly the ocean lays siege to the shore; how indefatigably every winter the batteringram of the billows smites on the coast-wall, and grinds it down. Every particle so torn away, or in gentler fashion gnawed away, helps to make a stratum. But this smiting and gnawing of the margin is as nothing to the atmospheric and aqueous abrasion of the surface. A stratum is substantially the strewing of what is swept off the land by rains and rivers on and over the floor of the deep; the tribute of the ocean of air to the ocean of water, of the waters that be above the firmament to the waters below. Here then is a great natural chronometer; the ocean is an hour-glass whose slowly precipitating and accumulating sand-drops tell off and register the life-periods of the earth. But to read that register other than roughly and approximately is beyond the best skill of man. The rates of deposition in ocean deltas, from which our data must be derived, vary with the volume and the rapidity of rivers, and the nature of the basins they drain. Then, again, the rate of deposition may have varied as widely at different epochs as it does in different regions. A high temperature with a moisture-loaded atmosphere, such as evidently prevailed in the Silurian period, supposes a strong impulse to the denuding agencies ; and the process would be accelerated in proportion as the denuded surfaces were, as they are believed to have been, yielding and friable. On the other hand, the phenomena of organic remains are often such as yield the clearest proof of extreme slowness of accumulation. 11 As a fair gauge of average rates of deposition, consistent with these phenomena, we may take the calculated growth of sediment in the Bay of Bengal, which is about an inch in a century. Such the stratum-making power of the Ganges, less indeed than that of the Nile, but far greater than that of the Rhine ; 12 and it measures off the age of the oldest water-woven rocks as approaching, at the least, one hundred millions of years. Observe, of the sedimentary rocks ; not of the globe, nor of life. The globe is indefinitely older ; life, as we shall see by and by, according to our present evidence, is relatively much more recent. Still, even on this estimate, and with this deduction, that is an aweinspiring vista which stretches upward to the dawnings of vitality on the earth. Any man who is nearing or passing the threescore - and - ten may form this rough reckoning to his own mind—that, for every year he has been alive, Life has lived at least a million. Suppose every human being in this populous city endowed with a life-lease of one thousand years, and each of these to be pieced on in succession to one another, this would no more than cover, if cover it did, the sweep of palæontological time. Or take the distance of the sun from the earth as miles, and thrust that into the stratified depths as years, you will let fall a plummet that will scarcely outfathom, if it even traverse, the abyss of that solemn antiquity.13 Mr. Darwin, therefore, has ample scope for all reasonable demands on the lapse of terrestrial time. To be sure, when he exacts three hundred millions of years for a process which might, according to the observed rates of sea-encroachment on a tolerably impressible coast-line, be more feasibly restricted to three, 14 he