The attempt to apply psychometric tests to the problem of racial differences has been unsuccessful not only because there are no pure races but even more because of the wide diversities of mental experience found within any one group. The application of psychology to the study of culture resolves itself to the study of individuals in terms of cultural situations in which individual behavior goes on. From this point of view, the study of culture becomes a problem in the study of cultural types. Adapting biological terminology to our need, we may call them "variants," "hybrids," and "mutants." The "variant" is a group functionary whose task is to dispose of the accumulating cultural lags by maintaining some degree of consistency between the philosophy and practices prevailing in the group. The"hybrid" is a form of discontinuous variant whose function is to adapt borrowed culture forms to the prevailing forms in his own group. The "mutant" is a genius-leader who conceives his task to be the change of the fun...