wealth, are the seats of active industries and dense populations,[23]
while their low reliefs present no serious obstacle to the numerous
highways across them. They, therefore, afford all conditions for
culture.

[Sidenote: Indirect effects in differentiation of colonial peoples.]

Let us take a different example. The rapid modification in physical and
mental constitution of the English transplanted to North America, South
Africa, Australia and New Zealand has been the result of several
geographic causes working through the economic and social media; but it
has been ascribed by Darwin and others to the effect of climate. The
prevailing energy and initiative of colonists have been explained by the
stimulating atmosphere of their new homes. Even Natal has not escaped
this soft impeachment. But the enterprise of colonials has cropped out,
under almost every condition of heat and cold, aridity and humidity, of
a habitat at sea-level and on high plateau. This blanket theory of
climate cannot, therefore, cover the case. Careful analysis supersedes
it by a whole group of geographic factors working directly and
indirectly. The first of these was the dividing ocean which, prior to
the introduction of cheap ocean transportation and bustling steerage
agents, made a basis of artificial selection. Then it was the man of
abundant energy who, cramped by the narrow environment of a Norwegian
farm or Irish bog, came over to America to take up a quarter-section of
prairie land or rise to the eminence of Boston police sergeant. The
Scotch immigrants in America who fought in the Civil War were nearly two
inches taller than the average in the home country.[24] But the ocean
barrier culled superior qualities of mind and character
also--independence of political and religious conviction, and the
courage of those convictions, whether found in royalist or Puritan,