Among the most noteworthy phenomena of modern times are the extensive exploitation of new and thinly settled countries by citizens of countries older and more thoroughly developed, and the vast increase in international trade. These movements are, of course, due largely to the improved facilities for travel and communication, which have brought nations together and made their interests coincide in a way and to an extent unknown to former generations. One of the resulting problems is the question as to the attitude which a given country is to take towards its citizens who have settled permanently in foreign lands, without any definite intention of obtaining naturalization as citizens thereof, and particularly whether it is to undertake to extend its protection to them, and, if so, to what extent.