The causes of the difference of our species have been the subject of as great a discrepance in opinion. Most of the Greek and Roman Historians have attributed it to the influence of climate; and amongst the moderns, Montaigne, Montesquieu, Buffon, and Zimmerman, have considered the modification of the individual and the degeneration of the offspring as the result of this external agency. Lord Kaimes, Hume, and many other philosophers, have entertained a contrary opinion. No doubt, the influence of climate may materially affect colour, stature, hair, features, and even the moral and intellectual character; but it must be considered as inadequate to act upon conformation. The prevalence of light colours in the animals of polar regions is well known: the arctic fox, the white bear, the snow-bunting, are striking instances of this peculiarity; but these circumstances are purely superficial. The skulls of these individuals are similar to those of the Europeans; nay, it is well known that light races are found among dark nations, and many protected parts of the body are blacker than those which are exposed. Buchanan tells us, that the Jews in Cochin are divided into white and black classes, though born under the same parallel; the white Jews having been known there for upwards of one thousand seven hundred years. Dr. Shaw and Bruce describe a race of fair people, near Mount Aurasius in Africa, with red hair and blue eyes, and who are, according to tradition, descended from the Vandals. We find the red Peruvian, the brown Malay, and the white Abyssinian in the very zones peopled by jet black races. This influence of temperature upon colour frequently varies according to the seasons. Pallas observed that even in domestic animals, such as the horse and cow, the coat is of a lighter colour in winter. The Siberian roe, red in summer, is white in the winter; the fur of the sable and the martin is much deeper in the warm months; and the squirrel and mustela nivalis, which become white in Siberia and Russia, do not change their hue in Germany. The winter coat, it has been observed by naturalists, is found far advanced in the preparatory autumn. This bounteous provision of nature seems to have been extended to the vegetable kingdom and it has been observed that the pellicle of onions is much thicker on the approach of a severe winter than on that of a more temperate season. But if further proof were necessary to impugn this doctrine respecting climate, we may adduce the fact of a woman having borne twins of different complexions, a white and a black. With all due respect to the much-lamented Bishop Heber, we must receive with some degree of hesitation his assertion that the Persian, Greek, Tartar, and Arabian inhabitants of India, assume, in a few generations, without any intercourse with the Hindoos, a deep blue tint, little lighter than that of a negro; and that the Portuguese, during three hundred years' residence