In the latter case how great have been the changes and how rapid the transitions from the conditions of one latitude to another; how different, too, the effects upon a series of generations moving along a line a thousand miles long, from north to south, from those upon a stream of population propagated along an equal distance east and west.

The former takes them through half the latitudes of the world. The latter keeps them within a single zone—Arctic, Equatorial, or temperate, as the case may be, the climatologic influences seconding, instead of counteracting those of blood, and that in a ratio progressing geometrically.

FOOTNOTES:

[184] For the meaning of this, see the note at the end of the volume.

[185] For the powers of this alphabet, see the note at the end of the volume.

[186] For the meaning of this, see the note at the end of the volume.

IAPETIDÆ.
DIVISIONS.