222 Darwin, and after Darwin. 



agree in giving the same answer up to a certain 

 point. For both theories would agree in supposing 

 that these islands would, at all events in large part, 

 derive their inhabitants from accidental or occasional 

 arrivals of wind-blown or water-floated organisms 

 from other countries especially, of course, from the 

 countries least remote. But, after agreeing upon 

 this point, the two theories must part company in 

 their anticipations. The special-creation theory can 

 have no reason to suppose that a small volcanic 

 island in the midst of a great ocean should be chosen 

 as the theatre of any extraordinary creative activity, 

 or for any particularly rich manufacture of peculiar 

 species to be found nowhere else in the world. On 

 the other hand, the evolution theory would expect 

 to find that such habitats are stocked with more or 

 less peculiar species. For it would expect that when 

 any organisms chanced to reach a wholly isolated 

 refuge of this kind, their descendants should forth- 

 with have started upon an independent course of 

 evolutionary history. Protected from intercrossing 

 with any members of their parent species elsewhere, 

 and exposed to considerable changes in their con- 

 ditions of life, it would indeed be fatal to the 

 general theory of evolution if these descendants, 

 during the course of many generations, were not to 

 undergo appreciable change. It has happened on 

 two or three occasions that European rats have been 

 accidentally imported by ships upon some of these 

 islands, and even already it is observed that their 

 descendants have undergone a slight change of ap- 

 pearance, so as to constitute them what naturalists 

 call local varieties. The change, of course, is but 



