414 RECAPITULATION. [Chap. XV. 



tions ; it can act only by short and slow steps. Hence the canon of 

 "Natura ncn facit saltum," which every fresh addition to our 

 knowledge tends to confirm, is on this theory intelligible. We can 

 see why throughout nature the same general end is gained by an 

 almost infinite diversity of means, for every peculiarity when once 

 acquired is long inherited, and structures already modified in many 

 different ways have to be adapted for the same general purpose. Wc 

 can, in short, see why nature is prodigal in variety, though niggard 

 in innovation. But why this should be a law of nature if each 

 species has been independently created, no man can explain. 



Many other facts are, as it seems to me, explicable on this theory. 

 How strange it is that a bird, under the form of a woodpecker, 

 should prey on insects on the ground; that upland geese which 

 rarely or never swim, should possess webbed feet ; that a thrush- 

 like bird should dive and feed on sub-aquatic insects ; and that a 

 petrel should have the habits and structure fitting it for the life of 

 an auk ! and so in endless other cases. But on the view of each 

 species constantly trying to increase in number, with natural 

 selection always ready to adapt the slowly varying descendants of 

 each to any unoccupied or ill-occupied place in nature, these facts 

 cease to be strange, or might even have been anticipated. 



Wo can to a certain extent understand how it is that there is 

 so much beauty throughout nature ; for this may be largely attri- 

 buted to the agency of selection. That beauty, according to our 

 sense of it, is not universal, must be admitted by every one who 

 will look at some venomous snakes, at some fishes, and at certain 

 hideous bats with a distorted resemblance to the human face. 

 Sexual selection has given the most brilliant colours, elegant 

 patterns, and other ornaments to the males, and sometimes to 

 both sexes of many birds, butterflies, and other animals. With 

 birds it has often rendered the voice of the male musical to the 

 female, as well as to our ears. Flowers and fruit have been 

 rendered conspicuous by brilliant colours in contrast with the green 

 foliage, in order that the flowers may be easily seen, visited, and 

 fertilised by insects, and the seeds disseminated by birds. How it 

 comes that certain colours, sounds, and fcrms should give pleasure 

 to man and the lower animals, — that is, how the sense of beauty 

 in its simplest form was first acquired, — we do not know any 

 more than how certain odours and flavours were first rendered 

 agreeable. 



As natural selection acts by competition, it adapts and improves 

 the inhabitants of each country only in relation to their co- 

 inhabitants : so that we need feel no surprise at the species of any 



