ARTIFICIAL AND NATURAL SELECTION 47 



inasmuch as they are accidental in relation to the 

 sifting process of natural selection. 



E. Natural Selection, or the Survival of the 

 Fittest. — Those animals which are most in harmony 

 with their surroundings will survive. Just as in the 

 breeding of animals by artificial selection, those 

 animals are selected to survive which have certain 

 favourable peculiarities, usually too slight for any 

 but a practised eye to detect; so under natural con- 

 ditions the possession of some useful variation, such 

 as a slight increase of speed, or power of endurance 

 or strength, or a keener sense of vision, will deter- 

 mine which shall be the survivors in a large herd of 

 animals. 



The action of natural selection is well shown by 

 the following example. Many insects of Madeira 

 have either lost their wings, or had them so much 

 reduced as to be useless for flight, while their allies 

 in Europe have them well developed. The explana- 

 tion of this is that Madeira, like other temperate 

 oceanic islands, is much exposed to sudden gales, 

 and the most fertile land being near the coast, the 

 insects if able to fly are liable to be blown out to sea 

 and lost. Year after year the individuals which had 

 the shortest wings, or which used them least, would 

 have an advantage, and so would survive. Hence 

 the survival in the island of the insects with the 

 smallest wings. 



In Kerguelen Island, one of the stormiest places 

 on the globe and a place entirely without shelter, 

 all the insects are incapable of flight, and most of 

 them are entirely destitute of wings. These insects 



