258 THE GENESIS OF SPECIES. [CHAP. 



ance of which " final causes " and " divine ideal archetypes " 

 alike depend. 



Thus then, if the cumulative argument put forward in 

 this book is valid, we must admit the insufficiency of " Nat- 

 ural Selection " both on account of the residuary phenomena 

 it fails to explain, and on account of certain other phenom- 

 ena which seem actually to conflict with that theory. We 

 have seen that though the laws of Nature are constant, yet 

 some of the conditions which determine specific change may 

 be exceptionally absent at the present epoch of the world's 

 history ; also that it is not only possible, but highly probable, 

 that an internal power or tendency is an important if not 

 the main agent in evoking the manifestation of new species 

 on the scene of realized existence, and that in any case, 

 from the facts of homology, innate internal powers to the 

 full as mysterious must anyhow be accepted, whether they 

 act in specific origination or not. Besides all this, we have 

 seen that it is probable that the action of this innate power 

 is stimulated, evoked, and determined by external condi- 

 tions, and also that the same external conditions, in the 

 shape of " Natural Selection," play an important part in the 

 evolutionary process : and finally, it has been affirmed that 

 the view here advocated, while it is supported by the facts 

 on which Darwinism rests, is not open to the objections 

 and difficulties which oppose themselves to the reception 

 of " Natural Selection," as the exclusive or even as the 

 main agent in the successive and orderly evolution of or- 

 ganic forms in the genesis of species. 



