312 DARWINISM STATED BY DARWIN HIMSELF. 



marks, and look 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 " Geographi- 

 cal Distribution," yet of these species a very large propor- 

 tion 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 favorable 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 favor- 

 able 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 pro- 

 duction of new species, on the whole I am inclined to 

 believe that largeness of area is still more important, es- 

 pecially 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 favorable 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 spe- 

 cies ; and if some of these many species become modified 

 and improved, others will have to be improved in a cor- 

 responding degree, or they will be exterminated. 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 con- 

 curred. Finally, I conclude that, although small isolated 



