18 NATURAL SELECTION i 



There must be a cause for them ; they must be the necessary 

 results of some great natural law. Now, if, as it has been 

 endeavoured to be shown, the great law which has regulated 

 the peopling of the earth with animal and vegetable life is, 

 that every change shall be gradual ; that no new creature 

 shall be formed widely differing from anything before exist- 

 ing ; that in this, as in everything else in nature, there shall 

 be gradation and harmony, then these rudimentary organs 

 are necessary, and are an essential part of the system of 

 nature. Ere the higher Vertebrata were formed, for instance, 

 many steps were required, and many organs had to undergo 

 modifications from the rudimental condition in which only 

 they had as yet existed. We still see remaining an antitypal 

 sketch of a wing adapted for flight in the scaly flapper of the 

 penguin, and limbs first concealed beneath the skin, and then 

 weakly protruding from it, were the necessary gradations 

 before others should be formed fully adapted for locomotion. 1 

 Many more of these modifications should we behold, and more 

 complete series of them, had we a view of all the forms which 

 have ceased to live. The great gaps that exist between fishes, 

 reptiles, birds, and mammals would then, no doubt, be 

 softened down by intermediate groups, and the whole organic 

 world would be seen to be an unbroken and harmonious 

 system. 



Conclusion 



It has now been shown, though most briefly and imper- 

 fectly, how the law that " Every species has come into existence 

 coincident both in time and space with a pre-existing closely allied 

 species" connects together and renders intelligible a vast 

 number of independent and hitherto unexplained facts. The 

 natural system of arrangement of organic beings, their geo- 

 graphical distribution, their geological sequence, the pheno- 

 mena of representative and substituted groups in all their 

 modifications, and the most singular peculiarities of anatomical 

 structure, are all explained and illustrated by it, in perfect 

 accordance with the vast mass of facts which the researches of 

 modern naturalists have brought together, and, it is believed, 



1 The theory of Natural Selection has now taught us that these are not the 

 steps by which limbs have been formed ; and that most rudimentary organs 

 have been produced by abortion, owing to disuse, as explained by Mr. Darwin. 



