OF EVOLUTION. 



what is the nature of the proof that would be 

 required of the geologist to establish its validity ? 

 He would be required to show, in the first place, 

 that there has been a steady advance in the type 

 of structural organization from first to last not a 

 necessary elimination of forms of low degree, but 

 an overbalancing of these by forms of a more 

 complicated or higher grade of structure. Evo- 

 lution does not hold, as some opponents of the 

 theory would lead us to suppose, that the progres- 

 sive modification of individual organic forms 

 need be, or indeed has been, one of continuous 

 advance ; it recognizes merely a general advance 

 for the entire organic frame, while it admits of indi- 

 vidual retardation or degeneration. Its progress or 

 procession is the equivalent of the progress seen in 

 the development of civilization ; the united world 

 advances, whereas individual tribes or nations 

 remain at a standstill, or even degenerate and decay. 

 Such is precisely the history of the organic devel- 

 opment of our planet ; new and more complicated 

 organic types are being continually evolved, but 



