Doubtless it would be preposterous to refer the structure of either woodpecker or mistletoe to the single agency of any one of these three causes; but neither Lamarck nor any other writer on evolution has, so far as I know, even contemplated this; the early evolutionists supposed organic modification to depend on the action and interaction of all three, and I venture to think that this will ere long be considered as, to say the least of it, not more preposterous than the assigning of the largely preponderating share in the production of such highly and variously correlated organisms as the mistletoe and woodpecker mainly to luck pure and simple, as is done by Mr. Charles Darwin’s theory. It will be observed that in the paragraph last quoted from, Mr. Darwin, _more suo_, is careful not to commit himself. All he has said is, that it would be preposterous to do something the preposterousness of which cannot be reasonably disputed; the impression, however, is none the less effectually conveyed, that some one of the three assigned agencies, taken singly, was the only cause of modification ever yet proposed, if, indeed, any writer had even gone so far as this. We knew we did not know much about the matter ourselves, and that Mr. Darwin was a naturalist of long and high standing; we naturally, therefore, credited him with the same good faith as a writer that we knew in ourselves as readers; it never so much as crossed our minds to suppose that the head which he was holding up all dripping before our eyes as that of a fool, was not that of a fool who had actually lived and written, but only of a figure of straw which had been dipped in a bucket of red paint. Naturally enough we concluded, since Mr. Darwin seemed to say so, that if his predecessors had nothing better to say for themselves than this, it would not be worth while to trouble about them further; especially as we did not know who they were, nor what they had written, and Mr. Darwin did not tell us. It would be better and less trouble to take the goods with which it was plain Mr. Darwin was going to provide us, and ask no questions. We have seen that even tolerably obvious conclusions were rather slow in occurring to poor simple-minded Mr. Darwin, and may be sure that it never once occurred to him that the British public would be likely to argue thus; he had no intention of playing the scientific confidence trick upon us. I dare say not, but unfortunately the result has closely resembled the one that would have ensued if Mr. Darwin had had such an intention. The claim to originality made so distinctly in the opening sentences of the “Origin of Species” is repeated in a letter to Professor Haeckel, written October 8, 1864, and giving an account of the development of his belief in descent with modification. This letter, part of which is quoted by Mr. Allen, {173a} is given on p. 134 of the English translation of Professor Haeckel’s “History of Creation,” {173b} and runs as follows:—