[Footnote 15: See Prof. W. A. Locy's _Biology and its Makers_. New York, 1908. Part II. "The Doctrine of Organic Evolution."] [Footnote 16: Presidential Address to the British Association meeting at Dublin in 1908.] [Footnote 17: See in particular Samuel Butler, _Evolution Old and New_, London, 1879; J. L. de Lanessan, "Buffon et Darwin," _Revue Scientifique_, XLIII. pp. 385-391, 425-432, 1889.] [Footnote 18: _op. cit._ p. 136.] [Footnote 19: See Ernest Krause and Charles Darwin, _Erasmus Darwin_, London, 1879.] [Footnote 20: Osborn, _op. cit._ p. 142.] [Footnote 21: See E. Perrier, _La Philosophie Zoologique avant Darwin_, Paris, 1884; A. de Quatrefages, _Darwin et ses Précurseurs Français_, Paris, 1870; Packard, _op. cit._; also Claus, _Lamarck als Begründer der Descendenzlehre_, Wien, 1888; Haeckel, _Natural History of Creation_, Eng. transl. London, 1879; Lang, _Zur Charakteristik der Forschungswege von Lamarck und Darwin_, Jena, 1889.] [Footnote 22: See Huxley's article "Evolution in Biology," _Encyclopaedia Britannica_ (9th edit.), 1879, pp. 744-751, and Sully's article, "Evolution in Philosophy," _ibid._ pp. 751-772.] [Footnote 23: See Haeckel, _Die Naturanschauung von Darwin, Goethe und Lamarck_, Jena, 1882.] [Footnote 24: _Origin of Species_ (6th edit.), p. xvii.] [Footnote 25: _The Life and Letters of Charles Darwin_, Vol. 1. p. 83. London, 1887.] [Footnote 26: A. R. Wallace, _My Life, a Record of Events and Opinions_, London, 1905, Vol. 1, p. 232.] [Footnote 27: _My Life_, Vol. 1. p. 361.] [Footnote 28: P. Geddes. article "Biology." _Chambers's Encyclopaedia._] [Footnote 29: _Origin of Species_ (6th edit.), p. xv.] [Footnote 30: _Life and Letters_, II, p. 301.] [Footnote 31: _Science Progress_, New Series, Vol. 1. 1897. "A Remarkable Anticipation of Modern Views on Evolution." See also Chap. VI. in _Essays on Evolution_, Oxford, 1908.] [Footnote 32: See Prof. Patrick Geddes's article "Variation and Selection," _Encyclopaedia Britannica_ (9th edit.) 1888.] II THE SELECTION THEORY BY AUGUST WEISMANN _Professor of Zoology in the University of Freiburg_ (_Baden_) I. THE IDEA OF SELECTION Many and diverse were the discoveries made by Charles Darwin in the course of a long and strenuous life, but none of them has had so far-reaching an influence on the science and thought of his time as the theory of selection. I do not believe that the theory of evolution would have made its way so easily and so quickly after Darwin took up the cudgels in favour of it if he had not been able to support it by a principle which was capable of solving, in a simple manner, the greatest riddle that living nature presents to us,--I mean the purposiveness of every living form relative to the conditions of its life and its marvellously exact adaptation to these.