Chapter 4

NATURAL SELECTION.

Natural Selection--its power compared with man's selection--its power on characters of trifling importance--its power at all ages and on both sexes--Sexual Selection--On the generality of intercrosses between individuals of the same species--Circumstances favourable and unfavourable to Natural Selection, namely, intercrossing, isolation, number of individuals--Slow action--Extinction caused by Natural Selection--Divergence of Character, related to the diversity of inhabitants of any small area, and to naturalisation--Action of Natural Selection, through Divergence of Character and Extinction, on the descendants from a common parent--Explains the Grouping of all organic beings

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