“The theory of natural selection” became “our theory” in 1869. The opinion of Agassiz accords excellently with the theory of descent with modification, but it is not easy to see how it bears upon the fact that lucky races are preserved in the struggle for life—which, according to Mr. Darwin’s title-page, is what is meant by natural selection. Again:— “_On the theory of descent with modification_, the great law of the long-enduring but not immutable succession of the same types within the same areas, is at once explained” (p. 340). Again:— “It must not be forgotten that, _on my theory_, all the species of the same genus have descended from some one species” (p. 341). “My theory” became “our theory” in 1869. Again:— “He who rejects these views on the nature of the geological record, will rightly reject _my whole theory_” (p. 342). “My” became “our” in 1869. Again:— “Passing from these difficulties, the other great leading facts in palæontology agree admirably with _the theory of descent with modification through variation and natural selection_” (p. 343). Again:— The succession of the same types of structure within the same areas during the later geological periods _ceases to be mysterious_, and _is simply explained by inheritance_ (p. 345). I suppose inheritance was not when Mr. Darwin wrote considered mysterious. The last few words have been altered to “and is intelligible on the principle of inheritance.” It seems as though Mr. Darwin did not like saying that inheritance was not mysterious, but had no objection to implying that it was intelligible. The next paragraph begins—“If, then, the geological record be as imperfect as I believe it to be, . . . the main objections _to the theory of natural selection_ are greatly diminished or disappear. On the other hand, all the chief laws of palæontology plainly proclaim, _as it seems to me_, _that species have been produced by ordinary generation_.” Here again the claim to the theory of descent with modification is unmistakable; it cannot, moreover, but occur to us that if species “have been produced by ordinary generation,” then ordinary generation has as good a claim to be the main means of originating species as natural selection has. It is hardly necessary to point out that ordinary generation involves descent with modification, for all known offspring differ from their parents, so far, at any rate, as that practised judges can generally tell them apart. Again:— “We see in these facts some deep organic bond, prevailing throughout space and time, over the same areas of land and water, and independent of their physical condition. The naturalist must feel little curiosity who is not led to inquire what this bond is. “This bond, _on my theory_, _is simply inheritance_, that cause which alone,” &c. (p. 350).