CHAP. rv r .] RESULTS OF NATURAL SELECTION. 77 



at any small isolated area, such as an oceanic island, although the 

 number of species inhabiting it is small, as we shall see in our 

 chapter on Geographical Distribution ; yet of these species a very 

 large proportion are endemic, that is, have been produced there 

 and nowhere else in the world. Hence an oceanic island at first 

 sight seems to have been highly favourable for the production of 

 new species. But we may thus deceive ourselves, for to ascertain 

 whether a small isolated area, or a large open area like a continent, 

 has been most favourable for the production of new organic forms, 

 we ought to make the comparison within equal times ; and this we 

 are incapable of doing. 



Although isolation is of great importance in the production of 

 new species, on the whole I am inclined to believe that largeness 

 of area is still more important, especially for the production of 

 species which shall prove capable of enduring for a long period, 

 and of spreading widely. Throughout a great and open area, not 

 only will there be a better chance of favourable variations, arising 

 from the large number of individuals of the same species there 

 supported, but the conditions of life are much more complex from 

 the large number of already existing species ; and if some of these 

 many species become modified and improved, others will have to 

 be improved in a corresponding degree, or they will be extermi- 

 nated. Each new form, also, as soon as it has been much 

 improved, will be able to spread over the open and continuous 

 area, and will thus come into competition with many other forms. 

 Moreover, great areas, though now continuous, will often, owing 

 to former oscillations of level, have existed in a broken condition ; 

 so that the good effects of isolation will generally, to a certain 

 extent, have concurred. Finally, I conclude that, although small 

 isolated areas have been in some respects highly favourable for 

 the production of new species, yet that the course of modification 

 will generally have been more rapid on large areas ; and what is 

 more important, that the new forms produced on large areas, 

 which already have been victorious over many competitors, will 

 be those that will spread most widely, and will give rise to the 

 greatest number of new varieties and species. They will thus 

 play a more important part in the changing history of the organic 

 world. 



In accordance with this view, we can, perhaps, understand 

 some facts which will be again alluded to in our chapter on 

 Geographical Distribution ; for instance, the fact of the produc- 

 tions of the smaller continent of Australia now yielding befora 

 those of the larger Europaeo- Asiatic area. Thus, also, it is that 

 continental productions have everywhere become so largely 

 naturalised on islands. On a small island, the race for life will 

 have been less severe, and there will have been less modification 



