Westermarck, who accepts the "charm of disparity," gives references, History of Human Marriage, p. 354.
Descent of Man. Part II, Chapter XVIII.
Bloch (Beiträge zur Ætiologie der Psychopathia Sexualis, Teil II, pp. 260 et seq.) refers to the tendency to admixture of races and to the sexual attraction occasionally exerted by the negress and sometimes the negro on white persons as evidence in favor of such charm of disparity. In part, however, we are here concerned with vague statements concerning imperfectly known facts, in part with merely individual variations, and with that love of the exotic under the stimulation of civilized conditions to which reference has already been made (p. 184).