_Tabula rasa_, 27, 24. Tegetmeier, W. B., 34. Teleological principles, 10, 16, 25. Theories, nature of, 5 et seq. Turbellaria, 28. Units, vital, biological, physiological, etc., 8, 40, 41, 53, 56, 65, 80. Useful modifications, value of initial stages of, 80-82. Utility, 11, 18, 33, 45, 48, 62, 63, 82. Variations, necessary, their constant presence, 26 et seq., 31 et seq., 61; generally, 3, 11-14, 61, 71 et seq. Waagen, 72. Wallace, 11, 25, 29, 51, 66, 81. Weldon, 36. Whale, hind leg of, 42, 56, 80. Whitman, C. O., 53. Wiesner, 40. Wigand, Albert, 11, 63. Wings of butterflies, 14 et seq., 47-52, 56. Wolff, K. F., 53, 62, 63, 69. "Worse" individuals, 76. Zero-point of variation, 36 et seq., 45, 74, 79. * * * * * Notes [1] _Neue Gedanken zur Vererbungsfrage, eine Antwort an Herbert Spencer._ Jena. 1895. [2] See Boltzmann, _Methoden der theor. Physik_, Munich, 1892. (In the Catalogue of the Mathematical Exhibit.) [3] Of late this saying of Newton's is frequently quoted as if Newton were a downright contemner of scientific hypotheses. But if we read the passage in question in its original context, we shall discover that his renunciation of hypotheses referred solely to a definite case, viz., to that of universal gravitation, of whose character Newton could form no conception and hence was unwilling to construct hypotheses concerning it. Indeed, such a wholesale repudiation of hypotheses is antecedently incredible on the part of the inventor of the emission-theory of light, in which, to speak of only one daring conjecture, "fits" were ascribed to the luminous particles. Compare Newton, _Philosophiae Naturalis Principia Mathematica_, second edition, 1714, page 484. [4] H. Hertz, _Die Principien der Mechanik_. [5] Hans Driesch, _Die Biologie als selbststaendige Grundwissenschaft_, Leipsic, 1893, p. 31, footnote. The sentence reads: "An examination of the pretensions of the refuted Darwinian theory, so called, would be an affront to our readers." [6] _Die Allmacht der Naturzuechtung._ A Reply to Herbert Spencer. Jena, 1893, p. 27 et seq. [Also in the _Contemporary Review_ for September, 1893.] [7] That is, by the law of exceedingly slow retrogression of superfluous characters, which may be designated the law of organic inertia. [8] _Materials for the Study of Variation with Especial Regard to Discontinuity in the Origin of Species._ London, 1895. [9] _Studien zur Descendenztheorie_, Leipsic, 1876. Vol. II. pp. 295 and 322. [10] Compare my essay, _Neue Gedanken zur Vererbungsfrage_, Jena, 1895, p. 10, second footnote.