Lo have so restricted a distribution that their frequency in the eucire sauple dropped below 2 percent, then they would of course enter the List of rare variants. The final column of able 2 presents the frequency per 1000 of variants for cach system, and the unweiehted average of all the systems. An unweighted averasze is employed to prevent an extensive study of a single system [vom dominating the picture, | By this approach, the average trequency with which variants aré encountered in the systems under consideration, on the basis of 16,724 determinations, is 0.6/1000 observations. “Some of the Uieronesian Islands have had extensive contact with other athnic groups, and there has in addition been active exchange among the various islands (22,23). The possibility must always be borne in wind that a rare variant may have been introduced from the outside, as pointed out by Blake et al (12) in connection with the LDH variant they encountered on Faraulep Atoll, which ig similar to the Calcutta-L vuriant widespread in-India, We note in this connection that the CA LT variant of Tashian et al (20) encottntered in the Chamorros of Guam and Saipan is clectrophoretically almilar to a variant encountered in Pilipinos (24), Indonesians (25), and Japanese (26); Guam and Saipan have well-documented historical contacts with these arcas. On the other hand, we restate the well-recognized caveat that electrophoretic identity of two variants is not synonymous with biochemical identity. Yhere is rapidly accumulating an extensive Literature on the frequency of rare variants Ina variety of populations. We mentioned earlier the