THE KINSHIP OF LIFE. 23 



increase is actually impossible; for more than a hundred 

 other species of similar birds are disputing the same ter- 

 ritory, and there can not be place or food for all. With 



such conditions, the struggle for exist- 

 The equilibrium , , 



ence between sparrow and sparrow, and 

 of Nature. 



between sparrows and other birds, grows 



yearly more severe. Each year now the sparrow gains a 

 little and other birds lose correspondingly, but sooner or 

 later with each species a point will be reached when the 

 loss exactly balances the increase. This produces a 

 condition of apparent equiliibrum the equilibrium of 

 Nature; a sort of armed neutrality which a superficial 

 observer mistakes for real peace and permanence. But 

 this equilibrium is broken as soon as any individual or 

 group of individuals appears that can do something 

 more than merely hold its own in a struggle for existence. 

 It is thus evident that throughout all Nature the 

 number of organisms born into life is far in excess of 

 the number of those which can come to 

 More organisms maturityi In every spe cies the majority 

 born than can , , . , ,, , , . 



mature never reach their full growth, and this 



is because, for one reason or another, 

 they can not do so. All live who can. Nature asks 

 each organism, Why should you live ? And those who 

 can not give an answer pass away. "So careful of the 

 type she seems ; so careless of the single life." It is 

 also evident, to use the language of Professor Bergen, 

 that "the killing will not be indiscriminate, but it will 

 first and mainly comprise those individuals which are 

 least able to resist the attack." It is this " weeding- 

 out " process in Nature, this " natural selection," which 

 in Darwin's view constitutes the essential cause of 

 change and progress. Of the many possible illustra- 

 tions of the action of " natural selection," one may serve 

 our purpose at present. 



