Chapter IV 



NATURAL SELECTION 

 I 



NATURE OF THE STRUGGLE FOR EXISTENCE 



Difficulty THERE is a struggle for existence perpetually going on and 

 of real- tnose individuals or species, who cannot contend against their 



ismgthat i . -. 1-111 



there is competitors or the physical conditions under which they have to 

 an / live, are eliminated. The survivors are the picked few out of 



struggle 



going on an enormous herd. 



It is very hard to realise this when taking a walk in the 

 country and looking upon an ordinary English landscape. The 

 oak trees stand apparently unassailable, making light of their 

 many insect enemies. The flowers seem full of superabundant 

 life and the bees seem to be no more than healthily busy. The 

 birds sing as if life for them were all jollity. The rabbits feed 

 as if stoats and other enemies were too rare to affect their 

 happiness. The ploughman does not go about his work as if 

 there were any danger of his being eliminated for want of 

 energy. Sometimes the scene is well described by Tennyson's 

 lines : 



" A sleepy land where under the same wheel 

 The same old rut would deepen year by year." 



Often the happiness and jollity is more apparent than the 

 sleepiness. Except on comparatively rare occasions when we 

 come upon a butcher-bird's larder, or see a sparrow-hawk after 

 small birds, or a stoat pursuing a rabbit, the struggle for exist- 

 ence is not forcibly obtruded upon us. 



Yet it is very easy to show that the struggle is very real and 

 that only a small minority survive. Take house - martins l and 



i Chelidon urbica. 

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