Yule, G. U., 144

Z

Zero Family, 168

Zygote, 26, 443

Zymotic, 443

Zulus, 284

* * * * *

FOOTNOTES

[1] See Woods, Frederick Adams, "Laws of Diminishing Environmental
Influences," _Popular Science Monthly_, April, 1910, pp. 313-336;
Huxley, J. S., _The Individual in the Animal Kingdom_, Cambridge and New
York, 1912. Pike, F. H., and Scott, E. L., "The Significance of Certain
Internal Conditions of the Organism in Organic Evolution," _American
Naturalist_, Vol. XLIX, pp. 321-359, June, 1915.

[2] There is one line of experiment which is simple and striking enough
to deserve mention--namely, ovarian transplantation. A description of
this is given in Appendix A.

[3] Galton, Francis, _Inquiries into Human Faculty_, 1907 edition, pp.
153-173. This volume of Galton's, which was first published in 1883, has
been reissued in Everyman's Library, and should be read by all
eugenists.

[4] What is said here refers to positive correlations, which are the
only kind involved in this problem. Correlations may also be negative,
lying between 0 and -1; for instance, if we measured the correlation
between a man's lack of appetite and the time that had elapsed since his
last meal, we would have to express it by a negative fraction, the minus
sign showing that the greater his satiety, the less would be the time
since his repast. The best introduction to correlations is Elderton's
_Primer of Statistics_ (London, 1912).

[5] Dr. Thorndike's careful measurements showed that it is impossible to
draw a hard and fast line between identical twins and ordinary twins.
There is no question as to the existence of the two kinds, but the
ordinary twins may happen to be so nearly alike as to resemble identical
twins. Accordingly, mere appearance is not a safe criterion of the
identity of twins. His researches were published in the _Archives of
Philosophy, Psychology and Scientific Methods_, No. 1, New York, 1905.

[6] _A First Study of the Inheritance of Vision and the Relative
Influence of Heredity and Environment on Sight._ By Amy Barrington and
Karl Pearson. Eugenics Laboratory (London), Memoir Series V.

[7] Dr. James Alexander Wilson, assistant surgeon of the Opthalmic
Institute, Glasgow, published an analysis of 1,500 cases of myopia in
the _British Medical Journal_, p. 395, August 29, 1914. His methods are
not above criticism, and too much importance should not be attached to