, and the thirteen between the extremes of 75 and 88 found
in France and Italy.[850] Japan stands in much the same ethnic relation
to Asia as Britain to Europe. She has absorbed Aino, Mongolian, Malay
and perhaps Polynesian elements, but by reason of her isolation has been
left free to digest these at her leisure, so that her population is
fairly well assimilated, though evidences of the old mixture can be
discerned.[851] In Corsica and Sardinia a particularly low cephalic
index, dropping in some communes to 73, and a particularly short stature
point to a rare purity of the Mediterranean race,[852] and indicate the
maintenance here of one ethnic type, despite the intermittent intrusion
of various less pure stocks from the Italian mainland, Africa,
Phoenicia, Arabia, and Spain. The location of the islands off the main
routes of the basin, their remoteness from shore, and the strong spirit
of exclusiveness native to the people,[853] bred doubtless from their
isolation, have combined to reduce the amount of foreign intermixture.

[Sidenote: Remoter sources of island populations.]

Islands do not
necessarily derive their population from the land that lies nearest to
them. A comparatively narrow strait may effectively isolate, if the
opposite shore is inhabited by a nautically inefficient race; whereas a
wide stretch of ocean may fail to bar the immigration of a seafaring
people. Here we find a parallel to the imperfect isolation of oceanic
islands for life forms endowed with superior means of dispersal, such as
marine birds, bats and insects.[854] Iceland, though relatively near
Greenland, was nevertheless peopled by far away Scandinavians. These
bold sailors planted their settlements even in Greenland nearly two
centuries before the Eskimo. England received the numerically dominant
element of its population from across the wide expanse of the North Sea,
from the bare but seaman-breeding coasts of Germany, Denmark and Norway,
rather than from the nearer shores of Gaul. So the Madeira and Cape
Verde Isles had to wait for the coming of the nautical Portuguese to
supply them with a population; and only later, owing to the demand for
slave labor, did they draw upon the human stock of nearby Africa, but
even then by means of Portuguese ships.

[Sidenote: Double sources.]

Owing to the power of navigation to bridge the intervening spaces of
water and hence to emphasize the accessibility rather than the isolation
of these outl