DARWIN'S THEORY. - 29 



the astonishingly great increase, is the Natural Extinc- 

 tion of large numbers. 



Those whom nature exempts from this wholesale de- 

 struction, are naturally those which are the fittest to 

 live, the strongest, and most vigorous; and, notably, 

 those who "at intervals of a thousand generations" or 

 so, have developed some character, or modification, 

 which gives them an advantage, in the general contest 

 for life, over their competitors, and over the hard con- 

 ditions of life. 



This selection, of the strongest and fittest, and of the 

 favorably modified organisms, as the ones of the num- 

 ber ordained to live, is what constitutes Darwin's 

 Natural Selection — a factor which depends necessarily 

 upon this Struggle for Existence. 



Natural Selection has nothing whatever to do, Dar- 

 win says, with the production, or appearance, of any of 

 the variations or improvements. How any favorable 

 modification, or variation, comes to present itself, Dar- 

 win insists that he is profoundly ignorant. But, after 

 the variation has appeared, this Natural Selection 

 merely preserves it, insures its transmission to offspring, 

 and so accumulates successive variations which arise, 

 independently of it, owing to " an innate tendency." 

 Natural Selection, Darwin says, does not at all cause 

 the variations which may occur. Their origin is inex- 

 plicable to him, he says ; but, " it acts exclusively by 

 the preservation and accumulation of those variations 

 after they have arisen." Variations occur in some 

 strange way, by " accident or chance," independently 

 of Natural Selection, though so to refer them to acci- 



