190 DARWINISM AND HURIAN LIFE 



it is our business to prove that the survivors survive 

 because they have the character in question. 



Illustrations op Natural Selection. — In the 

 1858 essay Darwin gave the following imaginary 

 illustration. Some dog-like animal Uves on rabbits, 

 and on hares, when it can get them ; the rabbits 

 become scarcer, and the hares more plentiful, so 

 the carnivore turns its attention to hares ; those 

 carnivores that varied in the direction of swiftness 

 and sharp-sightedness would get on best, would be 

 more successful as regards numbers and vigour of 

 offspring ; in a thousand generations there would 

 be a marked effect — as surely, he said, as grey- 

 hounds can be improved by selection and careful 

 breeding. 



Many insects in Madeira have reduced and 

 useless wings, or none, while their alUes in Europe 

 have them well developed. The Darwinian inter- 

 pretation is, that as Madeira, like similar islands, 

 is exposed to sudden gales, the flying insects have 

 been blown out to sea, while those that varied in 

 the direction of flightlessness have survived. It 

 is easy to make fun of this, as Samuel Butler did 

 when he said it was hke explaining our own 

 presence by the fact that our cousins, uncles, and 

 aunts had gone away. A Uttle reflection, however, 

 will show that the theory fits the facts, and our 

 confidence in the interpretation grows when we 

 find that other exposed and wind-swept islands 

 agree with Madeira in having flightless insects. 

 Thus, in the stormy and shelterless Kerguelen all 

 the insects (including a moth, several flies, and 

 many beetles) are flightless and most are wingless. 



Many Arctic mammals and birds — such as fox 

 and falcon — have a beautiful white colour ; what 



