Seite - 215 - in The Origin of Species

SUMMARY 215 her to destroy the yonnpf queens, her daughters, as soon as they are born, or to perish herself in the combat; for un- doubtedly this is for the good of the community ; and mater- nal love or maternal hatred, though the latter fortunately is most rare, is all the same to the inexorable principle of natural selection. If we admire the several ingenious contri- vances, by which orchids and many other plants are fertilised through insect agency, can we consider as equally perfect the elaboration of dense clouds of pollen by our fir-trees, so that a few granules may be wafted by chance on to the ovules? summary: the law of unity of type and of the conditions of existence embkaced by the theory of natural selection We have in this chapter discussed some of the difficulties and objections which may be urged against the theory. Many of them are serious ; but I think that in the discussion light has been thrown on several facts, which on the belief of independent acts of creation are utterly obscure. We have seen that species at any one period are not indefinitely vari- able, and are not linked together by a multitude of interme- diate gradations, partly because the process of natural selec- tion is always very slow, and at any one time acts only on a few forms ; and partly because the very process of natural selection implies the continual supplanting and extinction of preceding and intermediate gradations. Closely allied species, now living on a continuous area, must often have been formed when the area was not continuous, and when the conditions of life did not insensibly graduate away from one part to another. When two varieties are formed in two dis- tricts of a continuous area, an intermediate variety will often be formed, fitted for an intermediate zone ; but from reasons assigned, the intermediate variety will usually exist in lesser numbers than the two forms which it connects: con- sequently the two latter, during the course of further modi- fication, from existing in greater numbers, will have a great advantage over the less numerous intermediate variety, and will thus generally succeed in supplanting and extermi- nating it.