[Footnote 16: See A.W. Trettien. Creeping and Walking. American
Journal of Psychology, October, 1900, vol. 12, pp. 1-57.]
[Footnote 17: Constructive and Preventive Philanthropy, by Joseph Lee.
Macmillan, New York, 1902, chaps. x and xi.]
[Footnote 18: C.O. Bernies. Physical Characteristics of the Runner and Jumper.
American Physical Education Review, September, 1900, vol. 5, pp. 235-245.]
[Footnote 19: A Study in the Play Life of some South Carolina
Children. Pedagogical Seminary, December, 1900, vol. 7, pp. 459-478.]
[Footnote 20: Education by Plays and Games. Pedagogical Seminary,
October, 1894, vol. 3, pp. 97-133.]
[Footnote 21: An Essay on Laughter. Longmans, Green and Co., London, 1902,
p. 427 et seq.]
[Footnote 22: See Brand's Popular Antiquities of Great Britain, 3
Vols., London, 1883.]
[Footnote 23: Psychology of Tickling, Laughing, and the Comic, by G.
Stanley Hall and Arthur Allin. American Journal of Psychology,
October, 1897, vol. 9, pp. 1-41.]
[Footnote 24: I. Breuer and S. Freud. Studien über Hysterie. F.
Deuticke, Wien, 1895. See especially p. 177 et seq.]
[Footnote 25: See a valuable discussion by H. A. Carr. The Survival
Values of Play, Investigations of the Department of Psychology and
Education of the University of Colorado, Arthur Allin, Ph.D., Editor,
November, 1902, vol. 1, pp. 3-47]