an. 52] TO A. DE CANDOLLE. 497 
species, and origin. Well, he has got on about as 
= towards you as I have. It is clear enough that, 
s I thought at first, derivation of species is to be 
val word, and natural selection admitted. The only 
question is, whether this is enough. 
Ever your attached friend, 
. GRAY. 
TO A. DE CANDOLLE. 
CAMBRIDGE, February 16, 1863. 
I am disposed to join issue with you on the question 
of Linnezus’ definition of species. I have long pon- 
dered your discussion of the subject in “ Géographie 
Botanique,”’ and still think, on the supposition of 
the fixity of species (which Linneus 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 ily: 
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. Read- 
“ Memoirs of Augustin Pyramus De Candolle,” Am. Jour. Sct., 
xxxy. 1-10, 
