Abstract
1. Among the Japanese some individuals have‘single’eye-lids, while others have‘double’eye-lids. This difference occurs according as the lower edge of the fold of the eye-lid reaches beyond the margin of the real lid, or falls short of the latter. Statistical examination of 1340 males and 1765 females shows that in males the frequency of the single eye-lid exceeds that of the double eye-lid only slightly, while in females just the reverse is the case (the frequency of double eye-lids in percentage-male 45.22, female 53.09).
2. A number of pedigrees collected indicate that this character is determined by a set of Mendelian factors, the factor for the double eye-lid behaving, as a dominant to the factor for the single eye-lid.
3. The manifestation of the character is subject to some degree of irregularity, besides being sex-controlled. In general, the male has a tendency to have single eye-lids, while the female is more apt to acquire double eye-lids.
