^:t. 52.] TO A. DE CANDOLLE. 497 



species, and origin. Well, he has got on about as 

 far towards you as I have. It is clear enough that, 

 as I thought at first, derivation of species is to be 

 the word, and natural selection admitted. The only- 

 question is, whether this is enough. 



Ever your attached friend, 



A. Gray. 



TO A. DE CANDOLLE. 



Cameeidge, February 16, 1863. 



I am disposed to join issue with you on the question 

 of Linnaeus' definition of species. I have long pon- 

 dered your discussion of the subject in " Geographie 

 Botanique," and still think, on the supposition of 

 the fixity of species (which Linnseus of course had 

 in view), that between " community of descent " and 

 " likeness," the former and not the latter is the fun- 

 damental conception in the idea of species. We may 

 test this by inquiring whether of the two can be de- 

 rived from the other. The likeness, I suppose, is the 

 consequence of the community of descent. But, then, 

 as the likeness is a thing of degrees, and, according 

 to present probabilities, species may have only a rela- 

 tive and temporary fixity, your view will after all 

 have the advantage ; and the question of species will 

 come to be metaphysical or logical, rather than nat- 

 ural-historical. The worst of all is that there will 

 remain no objective basis or standard ; and species 

 will be what each naturalist thinks best so to con- 

 sider ! 



I am pleased to know that the view of my article 

 on the " Memoirs " ^ is well received by you. Kead- 



1 " Memoirs of Augustin Pyramus De Candolle," Am. Jour. Sci., 

 XXXV. 1-10. 



