egroid part of the continent. Intercourse was not easy,
and produced clear effects only in the case of Africa. Enlightenment
filtering in here was sadly dimmed as it spread. Moreover it was delayed
till the introduction from Asia of the horse and camel, which were not
native to Africa, and which, as Ratzel points out, alone made possible
the long journey across the Sahara. The opposite or peninsular sides,
running out as great spurs from the compacter land-masses of the north,
look southward into vacant wastes of water, find no neighbors in those
Antarctic seas. Owing to this unfavorable location on the edge of
things, they were historically dead until four centuries ago, when
oceanic navigation opened up the great sea route of the Southern
Hemisphere, and for the first time included them in the world's circle
of communication. But even when lifted by the ensuing Europeanizing
process, they only emphasize the fundamental dependence of the Southern
Hemisphere upon the superior geographical endowments of the Northern.

[Sidenote: Effect of continental structure upon historical development.]

The build of the land-masses influences fundamentally the movements and
hence the development of the races who inhabit them. A simple
continental structure gives to those movements a few simple features and
a wide monotonous distribution which checks differentiation. A manifold,
complex build, varied in relief and ragged in contour, breaks up the
moving streams of peoples, turns each branch into a different channel,
lends it a distinctive character through isolation, finally brings it up
in a _cul de sac_ formed by a peninsula or mountain-rimmed basin, where
further movement is checked and the process of local individualization
begins. Therefore great simplicity of continental build may result in
historical poverty, as in the flat quadrangle of European Russia, the
level plateau of Africa, and the smooth Atlantic slope of North America,
with its neatly trimmed outline. Complexity, abounding in contrasted
environments, tends to produce a varied wealth of historical
development. Africa lies on the surface of the ocean, a huge torso of a
continent, headless, memberless, inert. Here is no diversity of outward
form, no contrast of zonal location, no fructifying variety of
geographic conditions. Humanity has forgotten to grow in its stationary
soil. Only where the Suez Isthmus formed an umbilical cord uniting
ancient Egypt to the mother con