226 THE DOCTRINE OF DESCENT. 



leaving any progeny — we do not know the cause, 

 though we may yet be able to fathom it; but in this 

 and all similar cases the adherents of the doctrine of 

 Creation must confess the inadequacy of their theory 

 of belief. 



Our exposition has shown that the species now extant 

 are the progeny of organisms previously existing; the 

 present apportionment on the earth is therefore a con- 

 sequence of the distribution of the progenitors of the 

 present organisms, and of the manifold displacements 

 of land and water by which they were indirectly or di- 

 rectly affected. We cannot hope ever to picture to our- 

 selves a faithful representation of the perpetual transfor- 

 mations of the surface of the earth. Only, if this could 

 be accomplished, and if we, moreover, had an accurate 

 register of the animals at each period inhabiting the 

 former islands, continents, and oceans — only then could 

 the distribution of the present organisms be thoroughly 

 fathomed and established. But in thus acknowledging 

 the incompleteness of our statistical means, we are at 

 least able to lay down with certainty the course of in- 

 quiry. We must, in the first place, proceed in the 

 method of the older vegetal and animal geography to 

 ascertain the natural limits and regions of distribution; 

 and, secondly, to collate these facts with the facts of 

 the distribution of the former progenitors of the present 

 animate world as it was determined by the geological 

 conditions of those times. It is needless to say that 

 Darwin has furnished the outlines for this work also. 

 But among his followers two are specially worthy of dis- 

 tinction: Wallace, with his researches on the Malay 

 Archipelago,^" abounding in subtle observation; and 



