[167] Seashore, C. E., in _Psychol. Monogs,_ XIII, No. 1, pp. 21-60, Dec., 1910. See also Fletcher-Copp, _ubi sup._ Mrs. Copp declares that the gift of "positive pitch" or "absolute pitch," i. e., the ability to name any sound that is heard, "may be acquired, speaking very conservatively, by 80% of normal children," if they begin at an early age. It may be that this discrepancy with Seashore's careful laboratory tests is due to the fact that the pupils and teachers trained by Mrs. Copp are a selected lot, to start with. [168] The contributions on this subject are very widely scattered through periodical literature. The most important is Karl Pearson's memoir (1914), reviewed in the _Journal of Heredity_, VI, pp. 332-336, July, 1915. See also Gini, Corrado, "The Superiority of the Eldest," _Journal of Heredity_, VI, 37-39, Jan., 1915. [169] _Journal of Heredity_, VIII, pp. 299-302, July, 1917. [170] _Biometrika_, IV, pp. 233-286, London, 1905. [171] See, for example, _Journal of Heredity_, VIII, pp. 394-396, September, 1917. A large body of evidence from European sources, bearing on the relation between various characters of the offspring, and the age of the parents, was brought together by Corrado Gini in Vol. II, _Problems in Eugenics_ (London, 1913). [172] Davenport, Charles B., "The Personality, Heredity and Work of Charles Otis Whitman," _American Naturalist_, LI, pp. 5-30, Jan., 1917. [173] Gillette, John M., _Constructive Rural Sociology_, p. 89, New York, 1916. [174] Cook, O. F., "Eugenics and Agriculture," _Journal of Heredity_, VII, pp. 249-254, June, 1916. [175] Gillette, John M., "A Study in Social Dynamics: A Statistical Determination of the Rate of Natural Increase and of the Factors Accounting for the Increase of Population in the United States," _Quarterly Publications of the American Statistical Association,_ n. s. 116, Vol. XV, pp. 345-380, December, 1916. [176] The popular demand for "equality of opportunity" is, if taken literally, absurd, in the light of the provable inequality of abilities. What is wanted is more correctly defined as an equal consideration of all with an _appropriate_ opportunity for each based on his demonstrated capacities. [177] _Essays in Social Justice._ By Thomas Nixon Carver, Harvard University Press, 1915, pp. 168-169. [178] Answering the question "How Much is a Man Worth?" Professor Carver states the following axioms: "The value of a man equals his production minus his consumption." "His economic success equals his acquisition minus his consumption." "When his acquisition equals his production then his economic success equals his value." "It is the duty of the state to make each man's acquisition equal his production. That is justice." Of course, "production" is here used in a broad sense, to mean the real social value of the services rendered, and not merely the present exchange value of the services, or the goods produced.