Fuego, the
encroachments of sheep-farmers and gold-miners from Patagonia twenty
years ago, by fencing off the land and killing off the wild guanaco,
threatened the existence of this animal and of the Onas natives of the
island. These, soon brought to bay in that natural enclosure, attacked
the farmers, whose reprisals between 1890 and 1900 reduced the number of
the Onas from 2,000 to 800 souls.[307]

[Sidenote: Contrast of large and small areas in bio-geography.]

The same law holds good in bio-geography; here, too, area gives strength
and a small territorial foothold means weakness. The native flora and
fauna of New Zealand seem involved in the same process of extinction as
the native race. The Maoris themselves have observed this fact and
applied the principle to their own obvious fate. They have seen hardy
imported English grasses offering deadly competition to the indigenous
vegetation; the Norway rat, entering by European ships, extirpating the
native variety; the European house fly, purposely imported and
distributed to destroy the noxious indigenous species.[308] The same
unequal combat between imported plants and animals, equipped by the
fierce Iliads of continental areas, and the local flora and fauna has
taken place on the little island of St. Helena, to the threatened
destruction of the native forms.[309]

The preponderant migration of animals from the northern to the southern
hemisphere is attributed by Darwin to the greater extent of land in the
north, whereby the northern types have existed in greater numbers and
have been so perfected through natural selection and competition, that
they have surpassed the southern forms in dominating power and therefore
have encroached successfully.[310] Also the races and nations of the
northern continents have seriously invaded the southern land-masses and
are still expanding. It is the largest continent, Eurasia, which has
been the chief center of dispersal.

[Sidenote: Political domination of large areas.]

The Temperate Zone of North America will always harbor a more powerful
people than the corresponding zone of South America, because the latter
continent begins to contract and tapers off to a point where the other
at the northern Tropic begins to spread out. Therefore North America
possesses more abundantly all the advantages accruing to a continent
from a location in the Temperate Zone. The wide basis of the North Slavs
in Russia and Siberia has given them a