NATURAL SELECTION IN MAN 203 
have a strong influence on the mortality of later life. And there is 
another factor which may be operative, and that is the influence 
of unfavorable surroundings on the germ plasm. It is, of course, 
possible that many conditions leading to a high infant death 
rate may affect the germ plasm in such a way as to produce 
variations of an inferior kind. It is on this point that we are in 
most urgent need of more light. Selective agencies differ in their 
effect upon the general vitality of the organisms. The problem of 
how any agent of elimination may affect the race is complicated 
by its possible action in producing variations in the germ plasm. 
A high infant death rate caused by agencies with an injurious 
effect on the germ plasm instead of being a blessing in disguise 
might prove to be an index of racial decay. 
REFERENCES 
Ammon, O. Die natiirliche Auslese beim Menschen. C. Fischer, Jena, 1893. 
Zur Anthropologie der Badener, Jena, 1899. Die Gesellschaftsordnung und 
ihre natiirlichen Grundlagen, Jena, 1895. 
Beddoe, J. Selection in Man. Sci. Prog. 5, 384-397, 1896, and 6, 167-177, 1897. 
Beeton, M., and Pearson, K. Data for the Problem of Evolution in Man. II, A 
First Study of the Inheritance of Longevity and the Selective Death Rate in 
Man. Proc. Roy. Soc. 65, 290-305, 1900. On the Inheritance of the Duration 
of Life, and on the Intensity of Natural Selection in Man. Biometrica, 1, 50-89, 
190!. 
Beeton, M., Yule, G. U., and Pearson, K. Data for the Problem of Evolution in 
Man. V. On the Correlation between Duration of Life and the Number of 
Offspring. Proc. Roy. Soc. 67, 159-179, 1901. 
Bell, A. G. The Duration of Life and the Conditions Associated with Longevity: 
A Study of the Hyde Genealogy. Genealogical Record Office, Washington, 
D. C., 1918, p. 57- 
Blaschko, A. Natiirliche Auslese und Klassenteilung. Neue Zeit. No. 20, 615-624, 
1895. 
Blum, A. Eugenics and Obstetrics. Problems in Eugenics, 387-395, 1912. 
Carr Saunders, A. M. Pigmentation in Relation to Selection and to Anthropo- 
metric Characters. Biometrica, 354-384, 1912. 
Clark, L. P., and Stowell, W. L. A Study of Mortality in Four Thousand Feeble- 
Minded and Idiots. N. Y., Med. Jour. 97, 376-378, 1913. 
Debret, F. J. La Sélection Naturelle dans l’Espéce Humaine. Paris, 1901, pp. 92. 
De Candolle, A. Les Types Brun et Blond au Point de Vue de la Santé. Rev. 
Anthrop. 1887, 265-274. 
Elderton, E. M., and Pearson, K. Further Evidence of Natural Selection in Man. 
Biometrica, 10, 488-506, 1915. 
