Abstract
(1) The material consists of finger patterns of 303 sets of twins and 796 non-twin individuals.
(2) For the classification of patterns, two different schemes have been adopted: the one according to the type of pattern, and other invented by Bonnevie which is based upon ridge-counting.
(3) The result of ridge-counting shows that the coefficient of correlation between right and left hands of the same individual is substantially the same either in monozygotic or in dizygotic twins (nearly 0.9); the correlation between different individuals of the same set of monozygotic twins is nearly 0.9, while it is only 0.4 in dizygotic twins.
(4) The number of ridges seems to be determined by multiple factors which show neither complete dominance nor complete recessiveness. Also a sex-linked factor seems to take part.
(5) The heredity is less marked as to the type of pattern.
(6) There is no evidence for the inheritance of the tendency to form a radial loop.
(7) The tendency to twist (to form composite pattern) and the tendency to form elongate or circular pattern seem to be inherited, but the mode is difficult to determine in either case.
