Abstract
The chest breadth and depth of 60 male and 31 female Japanese-American hybrids were longitudinally examined over a period from 6 to 15 years of age. In both measurements, the hybrids showed a tendency to approach Americans, or to become remote from Japanese, with advancing age. In order to analyse the thoracal (viscera) and extrathoracal (soft tissues) growth separately, the ages at peak velocity of both measurements were examined correlatively in 41 hybrid girls. As a result, the examinees were divided into two groups: A and B. In group-A examinees, the thoracal viscera (lungs, heart, etc.) reached a maximal growth rate earlier than the extrathoracal soft tissues and organs (muscles, fat, and mammary glands). In them, also, the first sign of menstruation appeared prior to the beginning of rapid growth of the extrathoracal parts. The reverse was the case with the group-B examinees. Some other characteristics of both groups were demonstrated, and the genesis of these groups was discussed.
