I have been delighted to see your review of Haeckel (A review of Haeckel's 'Schopfungs-Geschichte.' The "Academy", 1869. Reprinted in 'Critiques and Addresses,' page 303.), and as usual you pile honours high on my head. But I write now (REQUIRING NO ANSWER) to groan a little over what you have said about rudimentary organs. (In discussing Teleology and Haeckel's "Dysteleology," Prof. Huxley says:--"Such cases as the existence of lateral rudiments of toes, in the foot of a horse, place us in a dilemma. For either these rudiments are of no use to the animals, in which case... they surely ought to have disappeared; or they are of some use to the animal, in which case they are of no use as arguments against Teleology."--('Critiques and Addresses,' page 308.) Many heretics will take advantage of what you have said. I cannot but think that the explanation given at page 541 of the last edition of the 'Origin' of the long retention of rudimentary organs and of their greater relative size during early life, is satisfactory. Their final and complete abortion seems to me a much greater difficulty. Do look in my 'Variations under Domestication,' volume ii. page 397, at what Pangenesis suggests on this head, though I did not dare to put in the 'Origin.' The passage bears also a little on the struggle between the molecules or gemmules. ("It is a probable hypothesis, that what the world is to organisms in general, each organism is to the molecules of which it is composed. Multitudes of these having diverse tendencies, are competing with one another for opportunity to exist and multiply; and the organism, as a whole, is as much the product of the molecules which are victorious as the Fauna, or Flora, of a country is the product of the victorious organic beings in it."--('Critiques and Addresses,' page 309.) There is likewise a word or two indirectly bearing on this subject at pages 394-395. It won't take you five minutes, so do look at these passages. I am very glad that you have been bold enough to give your idea about Natural Selection amongst the molecules, though I can not quite follow you. 1870 AND BEGINNING OF 1871. [My father wrote in his Diary:--"The whole of this year [1870] at work on the 'Descent of Man.'... Went to Press August 30, 1870." The letters are again of miscellaneous interest, dealing, not only with his work, but also serving to indicate the course of his reading.] CHARLES DARWIN TO E. RAY LANKESTER. Down, March 15 [1870]. My dear Sir,