Longitudinal Observation on the Chest Circumference and Sitting Height of Japanese-American Hybrids from 6 to 15 Years of Age

Abstract

The present longitudinal growth study was made on 36 male and 21 female Japanese-American hybrids to clarify age changes in mean values of the chest circumference and sitting height. Analysis was also made on age changes in size relative to stature in the same subjects.(1) In females, the chest circumference was greater in the hybrids than in the Japanese after puberty, probably because of the considerably better development of the breasts (mammae) in the hybrid girls. In males, there was a significant difference between the hybrids and Japanese only after 14 years of age.(2) As to the sitting height, the male negro hybrids were about one year behind in getting into an adolescent spurt, so that they were the smallest when they reached 12 years of age.(3) For the relative chest circumference, the female hybrids became greater rapidly than the female Japanese after 10 years of age. In male hybrids, the same rush of growth occurred after 14 years of age.(4) The pattern of age changes in the relative sitting height was not the same between the hybrids and Japanese. In the negro male hybrids, the relative sitting height was markedly smaller than the white hybrids and the Japanese all over the period from 6 to 15 years of age. Hereditary factors are considered most responsible for this difference.The authors are indebted to Dr. S. SAKASEGAWA, professor at the Nippon Veterinary and Zootechnical College, for his kind suggestions in preparing the English manuscript.