THEORY OF 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. 



