Xg blood group frequencies in some further populations.

Received August 5, I966. * Caylor-Nickel Clinic and Foundation, Bluffton, Indiana. t University of Michigan, Ann Arbor, Michigan. $ Mackay Memorial Hospital, Taipei, Taiwan. § American Mission, Box I, Bahrain, Arabian Gulf. principally of Swiss extraction. The effective population size is not known, but the level of inbreeding is extremely high. The population appears to deviate from random mating in the small samples so far studied, but the breeding structure is such that we presume this finding to be an artefact. The Grand Rapids and Bluffton Caucasian populations are each derived from obstetrical series in private general hospitals in their respective locations, and consist of married couples ascertained through confinement of the wife for delivery. The Negro population is comprised of the small number of Negro couples from the two hospital series, pooled, plus some unrelated American Negroes living in Grand Rapids at the time of testing, Most of the families in the Grand Rapids, Bluffton.