328 S. J. HOLMES. 



It is perhaps worth while to point out that the sex ratio of 

 offspring resulting from the mating of native-born with foreign- 

 born parents is lower that it is among the native-born. Such 

 matings do not necessarily represent the union of distinct ethnic 

 stocks to a much greater degree than the matings of either the 

 native or the foreign-born, although they probably do so to a 

 certain extent. If we may judge from my studies on the matings 

 falling in this class among the parents of college students, 1 more 

 than fifty per cent, of such mixed marriages would be between 

 persons of the same extraction. On the whole, the federal 

 statistics on births indicate that the sex ratio is little affected by 

 the crossing of different ethnic stocks. There are several factors 

 associated with educational, social, and economic status which 

 probably influence the sex ratio to a greater degree. 



The American Negro is to a considerable, but not precisely 

 ascertainable, extent a product of the union of very distinct 

 races. There are no extensive data on the sex ratio of mulatto 

 births as compared with that of the more nearly pure blacks. 

 But since mulattoes are relatively much more numerous in cities 

 than in the country, one may compare the sex ratios of Negroes in 

 urban and rural communities. I have done this for two years, 

 1922 and 1923, and have added the still-births and live births 

 together. The sex ratio for the cities of the Registration Area is 

 103.78, and for the rural districts, 106.35. It would be unsafe to 

 conclude, however, that race mixture lowers the sex ratio in this 

 case. The relation is more readily explained by the higher pro- 

 proportion of still-births among the urban Negroes. 



REFERENCES. 

 Cummings, J. 



'18 Negro Population in the United States, 1790-1915. Washington, D. C., 



Bureau of the Census, pp. 844. 

 Gini, C. 



'08 II sesso dal punto di vista statistico. Pelermo, Sandron, xxx +518 pp. 

 Heape, W. 



'09 The Proportion of the Sexes Produced by Whites and Colored Peoples in 



Cuba. Philos Trans. Roy. Soc. London. B, 200, 271-330. 

 Little, C. C. 



'19 Some Factors Influencing the Human Sex-ratio. Proc. Soc. Exp. Biol. 



Med. 16, 127-130. 

 Nichols, J. B. 



'07 The Numerical Proportions of the Sexes at Birth. Mem. Am. Anthrop. 



Ass'n. i, 249-300. 

 1 Jour. Heredity, 17,287-291, 1926. 



