An interesting and almost unique case is furnished by Iceland, where isolation under peculiar conditions of climate, food, and social life has created a somewhat different type both of body and of mental character from that of the Norwegians, although so far as blood goes the two peoples are identical, Iceland having been colonised from Western Norway a thousand years ago, and both Icelanders and Norwegians having remained practically unmixed with any other race--save that some slight Celtic infusion came to Iceland with those who migrated thither from the Norse settlements in Ireland, Northern Scotland, and the Hebrides--since the separation took place. But by far the most remarkable instance of race admixture is that furnished in our own time by the United States of North America, where a people of predominantly English stock (although there were in the end of the eighteenth century a few descendants of Dutchmen, with Germans, Swedes, and Ulster Irishmen, in the country) has within the last sixty years received additions of many millions of Celts, of Germans and Scandinavians, and of various Slavonic races. At least a century must elapse before it can be seen how far this infusion of new blood will change the type of American character as it stood in 1840. There are, however, two noteworthy differences between modern race fusions and those which belong to primitive times. One is that under modern conditions the influence of what may be called the social and political environment is probably very much greater than it was in early times. The American-born son of Irish parents is at forty years of age a very different creature from his cousin on the coast of Mayo. The other is that in modern times differences of colour retard or forbid the fusion of two races. So far as the Teutonic peoples are concerned, no one will intermarry with a negro; a very few with a Hindu, a Chinese, or a Malay. In the ancient world there was but little contact between white men and black or yellow ones, but the feeling of race aversion was apparently less strong than it is now, just as it was much less strong among the Spaniards and Portuguese in the sixteenth and seventeenth centuries than it is among Americans or Englishmen to-day. It is less strong even now among the so-called “Latin races;” and as regards the Anglo-Americans, it is much less strong towards the Red Indians than towards negroes. [Illustration: THE REMARKABLE INFLUENCE OF ENVIRONMENT ON PHYSICAL APPEARANCE