Seite - 48 - in The Origin of Species

48 ORIGIN OF SPECIES eties. See how different the leaves of the cabbage are, and how extremely alike the flowers ; how unlike the flowers of the heartsease are, and how alike the leaves; how much the fruit of the different kinds of gooseberries differ in size, colour, shape, and hairiness, and yet the flowers present very slight differences. It is not that the varieties which differ largely in some one point do not differ at all in other points; this is hardly ever,—I speak after careful observation,—per- haps never, the case. The law of correlated variation, the im- portance of which should never be overlooked, will ensure some differences ; but, as a general rule, it cannot be doubted that the continued selection of slight variations, either in the leaves, the flowers, or the fruit, will produce races differing from each other chiefly in these characters. It may be objected that the principle of selection has been reduced to methodical practice for scarcely more than three- quarters of a century ; it has certainly been more attended to of late years, and many treatises have been published on the subject; and the result has been, in a corresponding degree, rapid and important. But it is very far from true that the principle is a modern discovery. I could give several refer- ences to works of high antiquity, in which the full impor- tance of the principle is acknowledged. In rude and bar- barous periods of English history choice animals were often imported, and laws were passed to prevent their exportation: the destruction of horses under a certain size was ordered, and this may be compared to the "roguing" of plants by nur- serymen. The principle of selection I find distinctly given in an ancient Chinese encyclopaedia. Explicit rules are laid down bj some of the Roman classical writers. From pas- sages in Genesis, it is clear that the colour of domesticated animals was at that early period attended to. Savages now sometimes cross their dogs with wild canine animals, to im- prove the breed, and they formerly did so, as is attested by passages in Pliny. The savages in South Africa match their draught cattle by colour, as do some of the Esquimaux their teams of dogs. Livingstone states that good domestic breeds are highly valued by the negroes in the interior of Africa who have not associated with Europeans. Some of these facts do not show actual selection, but they show that the