THE INTRODUCTION OF NEW SPECIES. 25 



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 

 imperfectly, 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 geographical 

 distribution, their geological sequence, the phenomena 

 of representative and substituted groups in all their 

 modifications, and the most singular peculiarities of 

 anatomical structure, are all explained and illus- 

 trated by it, in perfect accordance with the vast 

 mass of facts which the researches of modern na- 

 turalists have brought together, and, it is believed, 

 not materially opposed to any of them. It also 

 claims a superiority over previous hypotheses, on 

 the ground that it not merely explains, but necessi- 

 tates what exists. Granted the law, and many of 

 the most important facts in Nature could not have 

 been otherwise, but are almost as necessary deduc- 

 tions from it, as are the elliptic orbits of the planets 

 from the law of gravitation. 



