of the invaders have dwindled and died out; or, as the blood is mixed with the ancient blood, has there been a change, part reversion and part assimilation, to the ancient type in its old surroundings? Do tint of skin, eyes and hair, shape of skull, and stature, change in the new environment, so as to be like those of the older people who dwelt in this environment? Do the intrusive races, without change of blood, tend under the pressure of their new surroundings to change in type so as to resemble the ancient people of the land? Or, as the strains mingled, has the new strain dwindled and vanished, from causes as yet obscure? Has the blood of the Lombard practically disappeared from Italy, and of the Visigoth from Spain, or does it still flow in large populations where the old physical type has once more become dominant? Here in England, the long-skulled men of the long barrows, the short-skulled men of the round barrows, have they blended, or has one or the other type actually died out; or are they merged in some older race which they seemingly supplanted, or have they adopted the tongue and civilization of some later race which seemingly destroyed them? We cannot say. We do not know which of the widely different stocks now speaking Aryan tongues represents in physical characteristics the ancient Aryan type, nor where the type originated, nor how or why it imposed its language on other types, nor how much or how little mixture of blood accompanied the change of tongue. The phenomena of national growth and decay, both those which can and those which cannot be explained, have been peculiarly in evidence during the four centuries that have gone by since the discovery of America and the rounding of the Cape of Good Hope. These have been the four centuries of by far the most intense and constantly accelerating rapidity of movement and development that the world has yet seen. The movement has covered all the fields of human activity. It has witnessed an altogether unexampled spread of civilized mankind over the world, as well as an altogether unexampled advance in man’s dominion over nature; and this together with a literary and artistic activity to be matched in but one previous epoch. This period of extension and development has been that of one race, the so-called white race, or, to speak more accurately, the group of peoples living in Europe, who undoubtedly have a certain kinship of blood, who profess the Christian religion, and trace back their culture to Greece and Rome.