Seite - 255 - in The Origin of Species

THEORYOF NATURAL SELECTION 25S shake, being the incidental result of the power of moving, gained for other and beneficial purposes. Whether, during the gradual development of climbing plants, natural selection has been aided by the inherited efifects of use, I will not pre- tend to decide ; but we know that certain periodical move- ments, for instance the so-called sleep of plants, are governed by habit. I have now considered enough, perhaps more than enough, of the cases, selected with care by a skilful naturalist, to prove that natural selection is incompetent to account for the incipient stages of useful structures ; and I have shown, as I hope, that there is no great difficulty on this head. A good opportunity has thus been afforded for enlarging a little on gradations of structure, often associated with changed func- tions,—an important subject, which was not treated at suf- ficient length in the former editions of this work. I will now briefly recapitulate the foregoing cases. With the giraffe, the continued preservation of the indi- viduals of some extinct high-reaching ruminant, which had the longest necks, legs, &c., and could browse a little above the average height, and the continued destruction of those which could not browse so high, would have sufficed for the production of this remarkable quadruped; but the prolonged use of all the parts together with inheritance will have aided in an important manner in their co-ordination. With the many insects which imitate various objects, there is no im- probability in the belief that an accidental resemblance to some common object was in each case the foundation for the work of natural selection, since perfected through the occa- sional preservation of slight variations which made the re- semblance at all closer; and this will have been carried on as long as the insect confinued to vary, and as long as a more and more perfect resemblance led to its escape from sharp- sighted enemies. In certain species of whales there is a ten- dency to the formation of irregular little points of horn on the palate; and it seems to be quite within the scope of nat- ural selection to preserve all favourable variations, until the points were converted first into lamellated knobs or teeth, like those on the beak of a goose,—then into short lamellae.