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 
