[190] Beeton, Mary, and Karl Pearson, _Biometrika_ I, p. 60. The actual correlation varies with the age and sex: the following are the results: COLLATERAL INHERITANCE Elder adult brother and younger adult brother .2290 +- .0194 Adult brother and adult brother .2853 +- .0196 Minor brother and minor brother .1026 +- .0294 Adult brother and minor brother -.0262 +- .0246 Elder adult sister and younger adult sister .3464 +- .0183 Adult sister and adult sister .3322 +- .0185 Minor sister and minor sister .1748 +- .0307 Adult sister and minor sister -.0260 +- .0291 Adult brother and adult sister .2319 +- .0145 Minor brother and minor sister .1435 +- .0251 Adult brother and minor sister -.0062 +- .0349 Adult sister and minor brother -.0274 +- .0238 [191] The method used is the ingenious one devised by J. Arthur Harris (_Biometrika_ IX, p. 461). The probable error is based on n=100. [192] A. Ploetz, "Lebensdauer der Eltern und Kindersterblichkeit," _Archiv fuer Rassen-u Gesellschafts-Biologie_, VI (1909), pp. 33-43. [193] Or it may be supposed that the environment is so good as to make a non-selective death less likely, and therefore such deaths as do occur must more frequently be selective. [194] Hibbs, Henry H., Jr., _Infant Mortality: Its Relation to Social and Industrial Conditions_, New York, 1916. [195] See Castle, W. E., _Heredity_, pp. 30-32, New York, 1911. [196] Doll, E. A., "Education and Inheritance," _Journal of Education_, Feb. 1, 1917. [197] Atwater's celebrated experiments proved that all the energy (food) which goes into an animal can be accounted for in the output of heat or work. They are conveniently summarized in Abderhalden's _Text-book of Physiological Chemistry_, p. 335. [198] In this connection see farther Raymond Pearl's review of Mr. Redfield's "Dynamic Evolution" (_Journal of Heredity_) VI, p. 254, and Paul Popenoe's review, "The Parents of Great Men," _Journal of Heredity_, VIII, pp. 400-408. [199] See Dr. Hrdlicka's communication to the XIXth International Congress of Americanists, Dec. 28, 1915 (the proceedings were published at Washington, in March, 1917); or an account in the _Journal of Heredity_, VIII, pp. 98 ff., March, 1917.