Except where specific types of legal procedure bring about the elimination of the defectives, it seems as if it must inevitably result that the operation of natural selection will continually increase the proportion of mental defectives above that existing in the original group. This factor of natural selection has not to our knowledge been given adequate consideration in any published investigation on delinquency. But if our estimate of its effects is at all justified, then most examinations of juvenile delinquents, especially in reform and industrial schools, have disclosed proportions of mental defectives distinctly in excess of the original proportion previously existent among the entire mass of all offenders. The reports of these examinations have given rise to quite erroneous impressions concerning the extent of criminality among the feeble-minded and its relation to the whole volume of crime, and have consequently led to inaccurate deductions. The feeble-minded are undoubtedly more prone to commit crime than are the average normals; but through disregard of the influences of this factor of natural selection, as well as of others, both the proportion of crime committed by mental defectives and the true proportion of mental defectives among delinquents and criminals have very often been exaggerated. D. ISOLATION AND NATIONAL INDIVIDUALITY 1. Historical Races as Products of Isolation[112] The continent of Europe differs from the other great land-masses in the fact that it is a singular aggregation of peninsulas and islands, originating in separate centers of mountain growth, and of enclosed valleys walled about from the outer world by elevated summits. Other continents are somewhat peninsulated; Asia approaches Europe in that respect; North America has a few great dependencies in its larger islands and considerable promontories; but Africa, South America, and Australia are singularly united lands. The highly divided state of Europe has greatly favored the development within its area of isolated fields, each fitted for the growth of a separate state, adapted even in this day for local life although commerce in our time binds lands together in a way which it did not of old. These separated areas were marvelously suited to be the cradles of peoples; and if we look over the map of Europe we readily note the geographic insulations which that remarkably varied land affords.