8 THE DEPTHS OF THE SEA. [CHAP. i. 



Eorbes defined and advocated what he called the 

 law of representation. He found that in all parts 

 of the world, however far removed, and however 

 completely separated by natural barriers, where the 

 conditions of life are similar, species and groups 

 of species occur which, although not identical, 

 resemble one another very closely ; and he found 

 that this similarity existed likewise between > groups 

 of fossil remains, and between groups of fossils 

 and groups of recent forms. Admitting the con- 

 stancy of specific characters, these resemblances 

 could not be accounted for by community of de- 

 scent, and he thus arrived at the generalization, 

 that in localities placed under similar circumstances, 

 similar though specifically distinct specific forms 

 were created. These he regarded as mutually repre- 

 sentative species. 



Our acceptance of the doctrines of specific centres 

 and of representation, or, at all events, the form in 

 which we may be inclined to accept these, depends 

 greatly upon the acceptance or rejection of the funda- 

 mental dogma of the immutability of species ; and 

 on this point there has been a very great change of 

 opinion within the last ten or twelve years, a change 

 certainly due to the remarkable ability and candour 

 with which the question has been discussed by Mr. 

 Darwin 1 and Mr. Wallace, 2 and to the genius of Pro- 



1 The Origin of Species by means of Natural Selection ; or, the 

 Preservation of Favoured Eaces in the Struggle for Life. By Charles 

 Darwin, M.A., F.R.S., L.S., G.S., &c. &c. London, 1859, and subse- 

 quent editions. 



2 Contributions to the Theory of Natural Selection. A Series of 

 Essays by Alfred Russel Wallace. London, 1870. 



