n the human
form differences such as distinguish separate species of the brute
creation. All races of men are nearly of like stature and size, varying
only by the accidents of climate and food favorable or adverse to their
full development. The number, shape, and uses of limbs and extremities
are alike, and internal construction is invariably the same. These are
circumstances the least acted upon by situation and temperature, and
therefore the surest tests of a particular species. Color is the most
obvious and the principal indication of difference in the human
families, and is evidently influenced to a great extent by the action of
the sun,[209] as the swarthy cheek of the harvest laborer will witness.
Under the equator we find the jet black of the negro; then the
olive-colored Moors of the southern shores of the Mediterranean; again,
the bronzed face of the Spaniard and Italian; next, the Frenchman,
darker than those who dwell under the temperate skies of England; and,
last, the bleached and pallid visages of the north. Along the arctic
circle, indeed, a dusky tint again appears: that, however, may be fairly
attributed to the scorching power of the sun, constantly over the
horizon, through the brief and fiery summer. The natives remain
generally in the open air during this time, fishing, or in the chase;
and the effect of exposure stamps them with a complexion which even the
long-continued snows can not remove. In the rigorous winter season, the
people of those dreary countries pass most of their time in wretched
huts or subterranean dwellings, where they heap up large fires to warm
their shivering limbs. The smoke has no proper vent in these
ill-constructed abodes; it fills the confined air, and tends to darken
the complexions of those constantly exposed to its influence.

The difference of color in the human race is doubtless influenced by
many causes, modifying the effect of position with regard to the
tropics. The great elevation of a particular district, its proximity to
the sea, the shades of a vast forest, the exhalations from extensive
marshes, all tend to diminish materially the power of a southern
sun.[210] On the other hand, intensity of heat is aggravated by the
neighborhood of arid and sandy deserts, or rocky tracts. The action of
long-continued heat creates a more permanent effect than the mere
darkening of the outer skin: it alters the character of those subtile
juices that display their color through t