ANCESTR Y AND CLA SSIFICA TlOtf. 237 



from a common source, from which the Vice- 

 roy has diverged through mimicry in its final 

 stage. 



These are only a few examples, but sufficient 

 to show in how many ways butterflies may vary 

 and how these variations may be appropriated for 

 the development of species ; the distinctions be- 

 coming gradually intensified into complete and 

 permanent diversity. This is natural selection. 

 And by the avidity with which natural selection 

 seizes every possible variation to produce new 

 forms, one would fairly suppose that its constant 

 action would lead to endless variety. And if on 

 this theory we should maintain that all existing 

 forms of animal life have sprung from a few origi- 

 nal sources, then we may fairly conclude that nat- 

 ural selection, by itself alone, would also lead to 

 inextricable confusion, through which it would be 

 impossible now to trace one thread of harmony. 

 That it is not so, that the groupings and relations 

 of structure among animals are clear to the human 

 mind, that they present an orderly arrangement 

 and a harmonious intercombination, which ap- 

 peals to his reason, is sufficient proof that natural 

 selection, in all its wondrous and pervading 

 power, acts under law, a law of evolution, which 

 is no slave to the forces of nature, but brings them 

 into subservience to its ends, a law which is 

 working out the plans of a Supreme Intelligence, 



