distinct were, after all, only exceedingly
persistent varieties, and that they had arisen by the modification
of some common stock, just as it is with good reason believed that
turnspits and greyhounds, carrier and tumbler pigeons, have arisen.

But there was a link wanting to complete the parallel. Where in nature
was the analogue of the breeder to be found? How could that operation
of selection, which is his essential function, be carried out by mere
natural agencies? Lamarck did not value this problem; neither did
he admit his impotence to solve it; but he guessed a solution. Now,
guessing in science is a very hazardous proceeding, and Lamarck's
reputation has suffered woefully for the absurdities into which his
baseless suppositions led him.

Lamarck's conjectures, equipped with a new hat and stick, as Sir Walter
Scott was wont to say of an old story renovated, formed the foundation
of the biological speculations of the 'Vestiges', a work which has done
more harm to the progress of sound thought on these matters than any
that could be named; and, indeed, I mention it here simply for the
purpose of denying that it has anything in common with what essentially
characterises Mr. Darwin's work.

The peculiar feature of the latter is, in fact, that it professes to
tell us what in nature takes the place of the breeder; what it is that
favours the development of one variety into which a species may run, and
checks that of another; and, finally, shows how this natural selection,
as it is termed, may be the physical cause of the production of species
by modification.

That which takes the place of the breeder and selector in nature is
Death. In a most remarkable chapter, 'On the Struggle for Existence',
Mr. Darwin draws attention to the marvellous destruction of life which
is constantly going on in nature. For every species of living thing,
as for man, "Eine Bresche ist ein jeder Tag."--Every species has its
enemies; every species has to compete with others for the necessaries
of existence; the weakest goes to the wall, and death is the penalty
inflicted on all laggards and stragglers. Every variety to which a
species may give rise is either worse or better adapted to surrounding
circumstances than its parent. If worse, it cannot maintain itself
against death, and speedily vanishes again. But if better adapted, it
must, sooner or later, "improve" its progenitor from the face of the
earth, and take its place. If circumsta