which will ultimately prevail and procreate new and dominant species.
As all the living forms of life are the lineal descendants of those
which lived long before the Silurian epoch, we may feel certain that
the ordinary succession by generation has never once been broken, and
that no cataclysm has desolated the whole world. Hence we may look with
some confidence to a secure future of equally inappreciable length. And
as natural selection works solely by and for the good of each being,
all corporeal and mental endowments will tend to progress towards
perfection.
It is interesting to contemplate an entangled bank, clothed with many
plants of many kinds, with birds singing on the bushes, with various
insects flitting about, and with worms crawling through the damp earth,
and to reflect that these elaborately constructed forms, so different
from each other, and dependent on each other in so complex a manner,
have all been produced by laws acting around us. These laws, taken in
the largest sense, being Growth with Reproduction; Inheritance which is
almost implied by reproduction; Variability from the indirect and
direct action of the external conditions
of life, and from use and disuse; a Ratio of Increase so high as to
lead to a Struggle for Life, and as a consequence to Natural Selection,
entailing Divergence of Character and the Extinction of less-improved
forms. Thus, from the war of nature, from famine and death, the most
exalted object which we are capable of conceiving, namely, the
production of the higher animals, directly follows. There is grandeur
in this view of life, with its several powers, having been originally
breathed into a few forms or into one; and that, whilst this planet has
gone cycling on according to the fixed law of gravity, from so simple a
beginning endless forms most beautiful and most wonderful have been,
and are being, evolved.
INDEX.
Aberrant groups, 429.
Abyssinia, plants of, 375.
365