[18] Cyril Burt: _The Distribution and Relations of Educational Abilities_, pp. 53-56. [19] Quotations from Galton: _Hereditary Genius_, ’92, pp. 61-62 and pp. 103-104. [20] Terman, Lewis: _The Intelligence of School Children_. Boston: Houghton Mifflin, 1919. [21] Woodworth, R. S.: _Dynamic Psychology_, p. 200. New York: Columbia University Press, 1918.