THE MIGRATION OF POPULATIONS 89 an essential to the active relief of difficulties arising through over-dense aggregations of the world’s peoples. In this connection it is also to be noted that it has already appeared that persons in one territory, antici- pating trouble for itself from population-growth, have advocated that another territory not under its political control directly or indirectly should freely open its borders to immigrants, because, according to the (uninformed) judgments of these persons, the other territory is capable of increasing its population-density. Since, however, the recipient country carries all the economic and political consequences of its immigration policy, such advocacy is unwarrantable, and dictation in the matter would but intensify the difficulties already in existence. Readiness to consign troubles to others is not an unknown feature even in national human conduct.