4 THE FOUNDATIONS OF THE 'ORIGIN OF SPECIES.' 



Then follows a comparison between rarity * and extinction, 

 which introduces the idea that the preservation and dominance 

 of existing species depend on the degree in which they are 

 adapted to surrounding conditions. In the first edition, he is 

 merely " tempted to believe in such simple relations as varia- 

 tion of climate and food, or introduction of enemies, or the 

 increased number of other species, as the cause of the succes- 

 sion of races." But finally (ist edit.) he ends the chapter by 

 comparing the extinction of a species to the exhaustion and 

 disappearance of varieties of fruit-trees, as though he thought 

 that a mysterious term of life was impressed on each species 

 at its creation. 



The difference of treatment of the Galapagos problem is of 

 some interest. In the earlier book, the American type of the 

 productions of the islands is noticed, as is the fact that the 

 different islands possess forms specially their own, but the 

 importance of the whole problem is not so strongly put 

 forward. Thus, in the first edition, he merely says : 



" This similarity of type between distant islands and con- 

 tinents, while the species are distinct, has scarcely been 

 sufficiently noticed. The circumstance would be explained, 

 according to the views of some authors, by saying that the 

 creative power had acted according to the same law over a 

 wide area." (ist edit. p. 474.) 



This passage is not given in the second edition, and the 

 generalisations on geographical distribution are much wider 

 and fuller. Thus he asks : 



" Why were their aboriginal inhabitants, associated ... in 

 different proportions both in kind and number from those 

 on the Continent, and therefore acting on each other in a 

 different manner why were they created on American types 

 of organisation ? " (2nd edit. p. 393.) 



* In the second edition, p. 146, of our ignorance of the causes of 

 the destruction of Niata cattle by rarity or extinction. The passage 

 droughts is given as a good example does not occur in the first edition. 



