[160] See an interesting series of five articles in The American Hebrew, Jan and Feb., 1917.
[161] Journal of Heredity, VIII, pp. 277-283, June, 1917.
[162] The Early Life of Abraham Lincoln, New York, 1896. For the Emancipator's maternal line see Nancy Hanks, by Caroline Hanks Hitchcock. New York, 1899.
[163] The Life of Pasteur by his son-in-law, René Vallery Radot, should be read by every student of biology.
[164] Hollingworth, H. L., Vocational Psychology, pp. 212-213, New York, 1916.
[165] Sir Francis Galton and C. B. Davenport have called attention to the probable inheritance of artistic ability and lately H. Drinkwater (Journal of Genetics, July, 1916), has attempted to prove that it is due to a Mendelian unit. The evidence alleged is inadequate to prove that the trait is inherited in any particular way, but the pedigrees cited by these three investigators, and the boyhood histories of such artists as Benjamin West, Giotto, Ruskin and Turner, indicate that an hereditary basis exists.
[166] The difficulty about accepting such traits as this is that they are almost impossible of exact definition. The long teaching experience of Mrs. Evelyn Fletcher-Copp (Journal of Heredity, VII, 297-305, July, 1916) suggests that any child of ordinary ability can and will compose music if properly taught, but of course in different degree.
[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.