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.

Acclimatisation, 139.

Affinities:  of extinct species, 329. of organic beings, 411.

Agassiz:  on Amblyopsis, 139. on groups of species suddenly appearing, 302, 305. on embryological succession, 338. on the glacial period, 366. on embryological characters, 418. on the embryos of vertebrata, 439. on parallelism of embryological development and geological succession, 449.

Algae of New Zealand, 376.

Alligators, males, fighting, 88.

Amblyopsis, blind fish, 139.

America, North:  productions allied to those of Europe, 371. boulders and glaciers of, 373.  South, no modern formations on west coast, 290.

Ammonites, sudden extinction of, 321.

Anagallis, sterility of, 247.

Analogy of variations, 159.

Ancylus, 386.

Animals:  not domesticated from being variable, 17. domestic, descended from several stocks, 19. acclimatisation of, 141. of Australia, 116. with thicker fur in cold climates, 133. blind, in caves, 137. extinct, of Australia, 339.