See, for example, John West's History of Tasmania, Vol. II, Launceston, Tasmania, 1852.

See Hollingworth, H. L., Vocational Psychology, p. 170, New York, 1916.

Net increase here refers only to the first year of life, and was computed by deducting the deaths under one year, in a ward, from the number of births in the same ward for the same year. For details of this study of the Pittsburgh vital statistics, see the Journal of Heredity, Vol. VIII, pp. 178-183 (April, 1917).

Quoted from Newsholme and Stevenson, The Decline of Human Fertility, London, 1906.

Heron, David, On the Relation of Fertility in Man to Social Status, London, 1906. The account is quoted from Schuster, Edgar, Eugenics, pp. 220-221, London, 1913.

Ztschft. f. Sozialwissenschaft, VII (1904), pp. 1 ff.

Two of the best known of these tribes are the "Jukes" and "Nams." "An analysis of the figures of the Jukes in regard to the birth-rate shows that of a total of 403 married Juke women, 330 reproduced one or more children and 73 were barren. The average fecundity, counting those who are barren, is 3.526 children per female. The 330 women having children have an average fecundity of 4.306 as compared with that of 4.025, based on 120 reproducing women in the Nam family."—Estabrook, A. H., The Jukes in 1915, p. 51, Washington, Carnegie Institution, 1916.