[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.