f living required of them, and
(3) the unwillingness of some of them to bring children into the world,
because of the feeling that these children would suffer from race
prejudice.

[186] One can not draw a hard and fast distinction between reason and
instinct in this way, nor deny to animals all ability to reason. We have
simplified the case to make it more graphic. The fact that higher
animals may have mental processes corresponding to some of those we call
reason in man does not impair the validity of our generalization, for
the present purpose.

[187] See _Jewish Eugenics and Other Essays_, By Rabbi Max Reichler, New
York, Bloch Publishing Co., 1916.

[188] Dublin, Louis I., "Significance of the Declining Birth Rate,"
_Congressional Record_, Jan. 11, 1918.

[189] At the request of Alexander Graham Bell, founder and director of
the Genealogical Record Office, Paul Popenoe made an examination and
report on these records in the fall of 1916. Thanks are due to Dr. Bell
for permitting the use in this chapter of two portions of the
investigation.

[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
n