[1] See “The Psychology of a Protozoon,” in the Amer. Jour. of Psychology, vol. X., No. 4, July, 1899, and the fuller papers there quoted.

[2] “The Psychic Life of Micro-Organisms,” 1889, p. 61.

[3] This paragraph is taken from “Animal Life and Intelligence,” p. 28.

[4] The following paragraphs are taken with some slight changes from “Animal Life and Intelligence,” pp. 30–35.

[5] D. H. Scott, “An Introduction to Structural Botany,” part ii., “Flowerless Plants,” pp. 70, 71.

[6] Ibid., p. 71.

[7] Kerner, “Natural History of Plants,” translated by F. W. Oliver, vol. i., p. 145.

[8] Kerner, “Natural History of Plants,” vol. i., p. 536.

[9] Kerner, “Natural History of Plants,” vol. ii., p. 132.

[10] Darwin, “Fertilization of Orchids,” 2nd edit., pp. 191, 192.

[11] “Mental Evolution in Animals,” p. 50.

[12] Ibid., p. 51.

[13] “A Text-book of Physiology,” 5th edit., part iii., p. 909.

[14] “A Text-book of Physiology,” 5th edit., part iii., pp. 911, 912.

[15] Professor Mark Baldwin has applied the term “organic selection” to the result of this interaction (American Naturalist for June and July, 1896). Cf. also H. F. Osborn (Science, Nov. 27, 1896); August Weismann (Romanes Lecture on “The Effects of External Influences on Development,” 1894), and “Germinal Selection,” Monist, Jan., 1896; and the author’s “Habit and Instinct,” ch. xiv., 1896.

[16] “Habit and Instinct,” p. 26.

[17] American Journal of Psychology, vol. ix., No. 1.

[18] Psychological Review, vol. vi., No. 3.

[19] “Naturalist in La Plata,” p. 88.

[20] Journal Asiatic Society of Bengal, lxvii., part ii., 1897, p. 614.

[21] Spectator, No. 120.

[22] Kirby and Spence, “Introduction to Entomology,” Letter xxvii. p. 537 (7th Edit., 1858).

[23] Cf. supra, p. 18.

[24] “The Play of Animals,” translated by Elizabeth L. Baldwin, p. 62.

[25] George W. and Elizabeth G. Peckham, “On the Instincts and Habits of the Solitary Wasps,” p. 231.

[26] “Lectures on Human and Animal Psychology,” pp. 388, 397, 399.

[27] “Instinct and Reason,” pp. 90, 92.

[28] “Instinct and Reason,” p. 91.

[29] Chapter I., Section V.

[30] “On the Habits and Instincts of the Solitary Wasps,” by George W. and Elizabeth G. Peckham (1898).

[31] “Mental Evolution in Animals,” p. 299.

[32] “Organic Evolution,” translated by J. T. Cunningham, p. 280.

[33] See A. G. Mayer “On the Mating Instinct of Moths.” Ann. and Mag. of Nat. Hist., ser. 7, vol. v., Feb., 1900, p. 183.

[34] Some of the observations on which the summary of results given in this section are founded are presented in some detail in “Habit and Instinct,” pp. 29–100.

[35] Psychological Review, May, 1899, p. 286.

[36] “Birds from Moidart and Elsewhere,” p. 107. Edinburgh: Douglas.

[37] Transactions of Northumberland and Durham Natural History Society, vol. viii., p. 213.

[38] “Mental Evolution in Animals,” p. 159.

[39] “Lectures on Human and Animal Psychology,” p. 401.

[40] “Instinct and Acquisition,” Nature, vol. xii., p. 507.

[41] On the nature of impulse, see infra, p. 235.

[42] “Lectures on Human and Animal Psychology,” p. 405.

[43] “Organic Evolution,” pp. 223, 263, 258, 279, 276, 298.

[44] “Essays on Heredity” (1889), p. 91.

[45] Op. cit., pp. 196–198.

[46] Professor Henry Osborn has also indicated the relationship referred to.

[47] “The Play of Animals,” p. 64.

[48] “Solitary Wasps,” p. 236.

[49] See D. Sharp, “Cambridge Natural History,” “Insects,” part ii., p. 293, and the original authorities cited on p. 294.

[50] This and the three succeeding paragraphs are taken from “Animal Life and Intelligence,” p. 425.

[51] “Animal Intelligence,” p. 59.

[52] “Instincts and Habits of the Solitary Wasps,” p. 55.

[53] Op. cit., p. 22.

[54] Op. cit., p. 215.

[55] “DÜrfen wir den Ameisen und Bienen psychische QualitÄten Zuschreiben.” PflÜger’s Archiv., lxx., 1898.

[56] “Solitary Wasps,” p. 219.

[57] Op. cit., pp. 131, 132.

[58] In a letter to Darwin, quoted by Romanes, “Mental Evolution in Animals,” p. 226.

[59] “The Structure and Life of Birds,” p. 335.

[60] Preface to “Harmonia Ruralis,” quoted by Yarrell, “British Birds,” vol. i., p. 541.

[61] American Journal of Psychology, vol. viii., no. 4, pp. 431–493.

[62] “Introduction to Comparative Psychology,” p. 255.

[63] “Introduction to Comparative Psychology,” p. 290.

[64] The Portfolio (1873), p. 27, “Canine Guests.”

[65] “Animal Intelligence,” pp. 28, 29.

[66] Nature, vol. xxxi., p. 200.

[67] Ibid., vol. li., p. 127.

[68] “Manual of Psychology,” p. 257.

[69] “Vegetable Mould and Earthworms,” p. 95.

[70] Wood’s Holl Biological Lectures (1898), p. 287.

[71] Supra, p. 44.

[72] “Mental Evolution in Man,” p. 27.

[73] “Intelligence of Animals,” p. 121.

[74] “Mental Development in the Child and the Race—Methods and Processes,” p. 278.

[75] “Animal Intelligence:” monograph supplement to Psychological Review, 1898, p. 61.

[76] Op. cit., pp. 263, 172, 201, 132, and 248 (note).

[77] “Animal Intelligence,” pp. 47–64.

[78] Op. cit., pp. 66, 14, 15.

[79] Cf. infra, p. 235.

[80] “The Play of Animals,” Eng. trans., p. 79.

[81] “Habit and Instinct,” pp. 174–180.

[82] “The Evolution of Mind in Man,” footnote, pp. 25, 26. Quoted in “Introduction to Comparative Psychology,” from which the comments on it are extracted.

[83] “The Speech of Monkeys.”

[84] “Scientific Lectures,” pp. 112, 118.

[85] Nature, vol. vii., p. 443.

[86] “The Senses of Animals,” p. 277.

[87] “Mental Evolution in Man,” p. 100.

[88] Op. cit., p. 175.

[89] Compare chap. xiii., on “The Perception of Relations,” in my “Introduction to Comparative Psychology.”

[90] Nineteenth Century, May, 1897, pp. 793–807.

[91] Sharp, “Insects,” part ii., p. 147.

[92] Nature, vol. lxii., p. 253 (July 12, 1900).

[93] The quotation is from “The Cambridge Natural History,” vol. vi., “Insects,” part ii., by David Sharp, F.R.S.; see pp. 145, 146.

[94] Sharp, op. cit., p. 147.

[95] G. A. J. Rothney, “Notes on Indian Ants,” Trans. Ent. Soc., 1889, p. 354.

[96] Sharp, op. cit., p. 226.

[97] Lord Avebury (Sir John Lubbock), quoted in Romanes’ “Animal Intelligence,” pp. 62, 63.

[98] Lord Avebury (Sir John Lubbock), “Scientific Lectures,” pp. 78, 79.

[99] Nature, vol. xlvii., p. 393 (Aug., 1893), where A. MÖller’s investigations are described by J. C. Willis.

[100] A. Bethe, “DÜrfen wir den Ameisen und Bienen psychische QualitÄten Zuschreiben,” PflÜger’s Archiv., lxx., 1898.

[101] See p. 37.

[102] Supra, p. 138.

[103] “Scientific Lectures,” pp. 80–82.

[104] Proceedings of the Zoological Society, 1874, p. 184.

[105] “Scientific Lectures,” 2nd edit., p. 140.

[106] Weismann, “Essays,” vol. ii., p. 50.

[107] Huxley, “Collected Essays,” vol. vii., p. 155.

[108] “The Descent of Man,” vol. i. p. 853, 2nd Ed., 1888. The quotations from Darwin in this paragraph and that which follows are somewhat condensed by a few omissions.

[109] Vol. xxviii., Sept. and Nov., 1890, pp. 337–354, 699–719.

[110] Nineteenth Century, Feb., 1888, p. 165. “Collected Essays,” vol. ix., p. 204.

[111] Op. cit., pp. 709, 710.

[112] Page 711.

[113] “Mutual Aid among Savages.” Nineteenth Century, vol. xxix. April, 1891, p. 538.

[114] “Descent of Man,” vol. i., p. 96.

[115] “Des SociÉtÉs Animales: Étude de Psychologie ComparÉe” (Paris, 1877).

[116] “Mutual Aid among Savages,” Nineteenth Century, April, 1891, pp. 539, 540.

[117] Page 63.

[118] Op. cit., p. 267; cf. supra, p. 138.

[119] G. F. Stout, “Manual of Psychology,” p. 268.

[120] Ibid., p. 318.

[121] “Manual of Psychology,” p. 84.

[122] “Habit and Instinct,” ch. ix., p. 186.

[123] “Letters on the Æsthetic Education of Mankind,” xxvii.

[124] “Principles of Psychology,” § 533.

[125] “On the Origin of Music,” pp. 231, 232.

[126] “The Play of Animals,” Eng. trans., p. 12.

[127] Op. cit., p. 7.

[128] Op. cit., p. 19.

[129] Op. cit., pp. 75, 76.

[130] “Manual of Psychology,” p. 327.

[131] Op. cit., pref., p. xx.

[132] Op. cit., p. 290.

[133] “Manual of Psychology,” p. 266.

[134] Op. cit., p. 314.

[135] “Descent of Man,” vol. ii., p. 60, 2nd edit. 1888.

[136] “The Play of Animals,” Eng. trans., p. 229.

[137] Quoted by Groos, op. cit., p. 259.

[138] “Descent of Man,” vol. ii., p. 77.

[139] Darwin, op. cit., p. 99.

[140] Quoted by Darwin, “Descent of Man,” vol. ii., p. 58.

[141] “Descent of Man,” vol. ii., p. 56.

[142] “Habit and Instinct,” p. 217.

[143] “Descent of Man,” vol. ii., p. 251.

[144] Op. cit., p. 137.

[145] “Darwinism,” p. 285.

[146] Op. cit., p. 293.

[147] Op. cit., p. 172.

[148] Op. cit., pp. 285, 286.

[149] Op. cit., p. 283.

[150] Op. cit., p. 243.

[151] Op. cit., p. 242.

[152] Op. cit., pref., p. xxii.

[153] Op. cit., p. 240.

[154] Op. cit., p. 244.

[155] “Manual of Psychology,” p. 85.

[156] “Manual of Psychology,” p. 23.

[157] Op. cit., p. 22.

[158] “Introduction to Comparative Psychology,” p. 53.

[159] “Manual of Psychology,” p. 266.

[160] “Animal Life and Intelligence,” p. 340.

[161] “Mutual Development in the Child and the Race,” p. 19.

[162] Supra, p. 270.

[163] “Animal Intelligence,” p. 413.

[164] Atalanta, Jan., 1889. Reprinted in “Animal Sketches,” p. 17.

[165] “The Play of Animals,” p. 122.

[166] Appendix to “Animal Intelligence,” p. 486.

[167] “Manual of Ethics,” p. 1.

[168] “Animal Life and Intelligence,” p. 404.

[169] “Animal Life and Intelligence,” p. 400. “Introduction to Comparative Psychology,” p. 369.

[170] “Animal Intelligence,” p. 444.

[171] “The Play of Animals,” p. 299.

[172] Op. cit., p. 145.

[173] “Manual of Ethics,” pp. 285, 286.

[174] Starcke, International Journal of Ethics, vol. ii., no. 3 (April, 1892), p. 348.

[175] “Manual of Psychology,” p. 234. “Displeasure” here means the feeling attitude antithetical to “pleasure.”

[176] Op. cit., p. 65.

[177] “Types of Ethical Theory,” vol. ii., f. 350.

[178] “Manual of Ethics,” p. 85.

[179] “Principles of Psychology,” vol. i., pt. ii., ch. ix. § 125.

[180] “Manual of Ethics,” p. 72.

[181] “Life and Letters,” vol. i., p. 310.

[182] Vol. i., pt. ii., ch. ix., § 124. I quote from the valuable “Epitome” prepared by Mr. Howard Collins, p. 214.

[183] “Principles of Biology,” revised and enlarged edit. (1898), p. 560.

[184] From “Animal Life and Intelligence,” p. 382.

[185] “Experiments on the Value of Vascular and Visceral Factors for the Genesis of Emotion,” Proc. Roy. Soc., vol. lxvi., pp. 390–403 (1900).

[186] “Manual of Psychology,” p. 288.

[187] “Manual of Psychology,” p. 132.

[188] See Huxley’s book on “The Crayfish,” in the International Science Series, p. 108.

[189] Journal of Morphology, vol. ix. Quoted by Professor C. S. Sherrington in The Marshall Hall Address, “On the Spinal Animal” (reprinted from Medico-Chirurgical Transactions, vol. 82), p. 4.

[190] “The Spinal Animal,” p. 5.

[191] Op. cit., p. 23.

[192] “Collected Essays,” vol. i., essay on “Animal Automatism,” p. 224.

[193] Op. cit., pp. 20, 21.

[194] Op. cit., p. 29.

[195] Op. cit., p. 18.

[196] Vide supra, p. 33.

[197] “Collected Essays,” vol. i., p. 240.

[198] Op. cit., pp. 238, 239.

[199] Vide supra, p. 285.

[200] “Naturalist in La Plata,” pp. 280, 281.

[201] “Psychology for Teachers,” p. 70.

[202] Supra, p. 36.

[203] Supra, p. 13.

[204] “Collected Essays,” vol. i., p. 239.