The chief influence which, in the case of two races mingling, determines the preservation or extinction of types or national features, is simply the numerical proportion existing between the two races thus amalgamating. When races meet and mix on equal terms, and with no natural repugnance to each other (in other words, _cæteris paribus_), the relative number of the two races decides the question—the type of the smaller number, in this hypothetical case, inevitably disappearing in the long run. Take, for example, a thousand white families and fifty black ones—place them on an island, and let them regularly intermarry; and the result would be, that in the course of time the black type would disappear, although there is reason to believe that traces of it would “crop out” during a very long period. And if two fair-skinned races were brought into contact in a similar manner, and in similar proportions, the extermination of the less numerous one would be even sooner effected. The operation of this law is well illustrated in the lower animals. Cross two domestic animals of different breeds—take the offspring and cross it with one of the parent stocks, and continue this process for a few generations, and the result is that the one becomes swallowed up in the other. This is the theory; but in the actual world races never intermarry with such theoretical regularity and indifference. Each community of mankind has, as its conservative element, a tendency to form unions within its own limits; and if a foreign element is once introduced into a population, the operation of this predilection tends to preserve the type of the lesser number for a much longer period than mere theory would assign to it. The stranger-hating and obstinate-tempered Bretons and Basques, for instance, by intermarrying among themselves, have thus preserved the type of the old Iberians through three thousand years, although surrounded on all sides by the fair-haired Celts. In the case of a conquering race like the Franks and Normans, there is generally less isolation than this; but then, the way in which the amalgamation between the conquerors and the conquered takes place, is such as to give a great advantage to the former. The sons of the conquerors may wed the daughters of the conquered, for the sake of their lands; but it is comparatively seldom that the daughters of the invaders will condescend to tarnish their scutcheon by becoming wedded to and merged in the class of the vanquished. The principle of caste is all-pervading, even when nominally repudiated; and thus, as the male ever influences most directly the type of the offspring, a small number of conquerors may for long perpetuate their line in comparative purity, even though surrounded by myriads of a different race.