178 Charles Darwin. 



noticed, while the others, presenting a marked con- 

 trast are seen, and devoured. This continues year in 

 and year out ; crabs which are conspicuous are eaten, 

 and the tendency is to weed them out, leaving those 

 which bear a resemblance to their surroundings. 

 These breed and produce others ; some of which 

 mimic the weed, and some do not. The latter are 

 soon picked up by their enemies, the others being 

 preserved to perpetuate their kind through the 

 agency of the bird that acts in the place of the 

 intelligent breeder. 



We see, then, as Darwin believed, that nature is 

 doing almost exactly what man does in producing 

 varieties. 



In the life of these animals there is a strife or 

 struggle for existence with the conditions that work 

 against them. Some survive, and only those which 

 are the fittest to carry on the work of perpetuation. 

 The struggle, the silent combats or tendencies to 

 survive, are what Darwin calls natural selection, while 

 Herbert Spencer styles it the survival of the fittest 

 I — terms which have become bywords in their famili- 

 1 arity to the readers of the present century. 

 ' An instance in plant life may still further illustrate 

 the point that accident, a peculiarity, a series of con- 

 ditions — climate, food, etc., may act in time in evolv- 

 ing from one form a variety of the same. We will 

 assume, taking an adapted example of Darwin's, 

 that the earth in a certain field on Staten Island pos- 

 sesses accidentally certain ingredients or qualities 

 which impart to the plant growing in it peculiar 

 strength to certain tissues, or such nourishment that 



