ABSTRACT
When the progress of mental development is followed, certain differences are noted in the general form of this progress, depending upon whether the children observed are in one environment or another, from one country or another, of this race or that, and also whether the boys and girls are examined separately. The differences in development which are noted among children submitted to similar or identical education are indications of mental differences betrayed among adults, from the point of view of the average level, and especially from the point of view of the mental type.
