an their immediate surroundings. In fact, the history
of North America has been perhaps more profoundly influenced by man's
inheritance from his past homes than by the physical features of his
present home. It is indeed of vast importance that trade can move freely
through such natural channels as New York Harbor, the Mohawk Valley, and
the Great Lakes. It is equally important that the eastern highlands of
the United States are full of the world's finest coal, while the central
plains raise some of the world's most lavish crops. Yet it is probably
even more important that because of his inheritance from a remote
ancestral environment man is energetic, inventive, and long-lived in
certain parts of the American continent, while elsewhere he has not the
strength and mental vigor to maintain even the degree of civilization to
which he seems to have risen.

Three streams of migration have mainly determined the history of
America. One was an ancient and comparatively insignificant stream from
Asia. It brought the Indian to the two great continents which the white
man has now practically wrested from him. A second and later stream was
the great tide which rolled in from Europe. It is as different from the
other as West is from East. Thus far it has not wholly obliterated the
native people, for between the southern border of the United States on
the one hand, and the northern borders of Argentina, Chile, and Uruguay
on the other, the vast proportion of the blood is still Indian. The
European tide may in time dominate even this region, but for centuries
to come the poor, disinherited Indians will continue to form the bulk of
the population. The third stream flowed from Africa and was as different
from either of the others as South is from North.

The differences between one and another of these three streams of
population and the antagonisms which they have involved have greatly
colored American history. The Indian, the European, and the Negro
apparently differ not only in outward appearance but in the much more
important matter of mentality. According to Brinton * the average brain
capacity of Parisians, including adults of both sexes, is 1448 cubic
centimeters. That of the American Indian is 1376, and that of the Negro
1344 cubic centimeters. With this difference in size there appears to
be a corresponding difference in function. Thus far not enough accurate
tests have been made upon Indians to enable us to draw reliable
conc