Note 17 — Chapter XIV · THE MULTIPLICATION OF EFFECTS.

Had this paragraph, first published in the Westminster Review in 1857, been written after the appearance of Mr. Darwin’s work on The Origin of Species, it would doubtless have been otherwise expressed. Reference would have been made to the process of “natural selection,” as greatly facilitating the differentiations described. As it is, however, I prefer to let the passage stand in its original shape: partly because it seems to me that these successive changes of conditions would produce divergent varieties or species, apart from the influence of “natural selection” (though in less numerous ways as well as less rapidly); and partly because I conceive that in the absence of these successive changes of conditions, “natural selection” would effect comparatively little. Let me add that though these positions are not enunciated in The Origin of Species, yet a mutual friend gives me reason to think that Mr. Darwin would coincide in them; if he did not indeed consider them as tacitly implied in his work.