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This fundamental subject of Natural Selection will be treated at some length in the fourth chapter; and we shall then see how Natural Selection almost inevitably causes much Extinction of the less improved forms of life and induces what I have called Divergence of Character.

Charles Darwin (1870). “On the Origin of Species by Means of Natural Selection: Or The Preservation of Favored Races in the Struggle for Life”, p.12
This fundamental subject of Natural Selection will be treated at some length in the fourth chapter; and we shall then see how Natural Selection almost inevitably causes much Extinction of the less improved forms of life