152 THE ORIGIN OF SPECIES 



1 smull, either from being surrounded by barriers, or from 



\ having very peculiar physical conditions, the total num- 

 ber of the inhabitants will be small; and this will retard 

 the production of new species through natural selection, 

 \^y decreasing the chances of favorable variations arising. 

 The mere lapse of time by itself does nothing, either 

 for or against natural selection. I state this because it 

 has been erroneously asserted that the element of time 

 has been assumed by me to play an all -important part 

 in modifying species, as if all the forms of life were 

 necessarily undergoing change through some innate law. 



> Lapse of time is only so far important, and its impor- 

 tance in this respect is great, that it gives a better chance 

 of beneficial variations arising and of their being selected, 

 accumulated, and fixed. It likewise tends to increase the 

 direct action of the physical conditions of life, in relation 



' to the constitution of each organism. 



If we turn to nature to test the truth of these re- 

 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 

 favorable for the production of new organic forms, we 

 ought to make the comparison within equal times; and 



this we are incapable of doing. 

 Jk . . . 



^^ j Although isolation is of great importance in the pro- 



