ure-laden equatorial atmosphere clothes the adjacent islands and firm land in emerald verdure. Upon the same parallel of latitude are the great Sahara Desert of Africa, and the wilderness of luxuriant billowy foliage of the American Isthmus. In warm, moist climates, such species of animal life attain the fullest development as are dependent upon the aqueous and herbous agencies. In tropical America are seen the largest reptiles, the most gorgeous insects,—there the inhabitants of warm marshes and sluggish waters assume gigantic proportions, while only upon the broad inland prairies or upon elevated mountain ranges, away from the influences of warm waters and humid atmospheres, are found the buffalo, bear, and elk. The very complexion and temperament of man are affected by these vegetative and umbrageous elements. Unprotected from the perpendicular rays of the sun, the African is black, muscular, and cheerful; under the shadow of primeval forest, man assumes a coppery hue, lacking the endurance of the negro, and becomes in disposition cold and melancholy.
And again, if we look for the natural causes which tend to promote or retard association, we find in climates and continental configurations the chief agencies. The continent of the two Americas, in its greatest length, lies north and south, the eastern continental group extends east and west. Primitive people naturally would spread out in those directions which offered the least change of climate from that of the primitive centre. Obviously, variations of climate are greater in following a meridian than along a parallel of latitude. Thus, the tropical man passing along a meridian is driven back by unendurable cold, while a continent may be traversed on any parallel, elevations excepted, with but little variation in temperature. A savage, exposed and inexperienced, not knowing how to protect himself against severe changes of climate, could not travel far in a northerly or southerly direction without suffering severely from the cold or heat;
