The elephant is the only quadruped on which a domestic state has never had any influence, because in that state it will not propagate, and consequently cannot transmit to its species those defects which its servile condition might occasion. The varieties in the elephant are only slight, and almost individual: its natural colour is black; some of them, however, are red, and others white, but those are very few in number. The size of the elephant also varies, according to the longitude rather than the latitude of the climate. Under the torrid zone, where it is, as we may say, shut up, and under the same line, in the eastern parts of Africa, it attains fifteen feet in height; whereas in the western parts of the same country it only arrives to the height of ten or eleven feet, which proves, that though great heat is necessary to the full expansion of its body, yet excessive heat reduces it to less dimensions. The rhinoceros seems to be of a more uniform and less variable size, and only differs in its own breed by that singular character which distinguishes it from every other animal, namely, the great horn on its nose. This horn is single in the Asiatic rhinoceros, and double in the African. I shall not speak here of the varieties which are found in every species of carnivorous animals, as they are extremely slight; because all animals which feed on flesh are the least dependent on man; and besides, this nutriment being already prepared by Nature, they receive scarcely any of the qualities of the soil they inhabit; besides, being endowed with strength and weapons, they have the power of chusing their own climate: consequently the three causes of change, alteration, and degeneration, of which we have spoken, can have but very slight and trivial effect on them. After this glance at the variations peculiar to each species, a more important consideration presents itself, that of the change of the species themselves; that ancient and immemorial degeneration made in each family, or in every genus, under which we may comprehend the proximating species. Among all terrestrial animals there are only a few detached species, which, like the human, at once compose both species and genus. The elephant, the rhinoceros, the hippopotamus, and the giraffe, form genera, or simple species, which propagate only in a direct line, and have no collateral branches; every other appears to form families, in which one principal trunk is generally to be recognized, and whence issues several different branches, so much the more or less numerous as the individuals in each species are barren or prolific.