DISTINCT CENTRES OF CREATION 473 
is right, and that there are not 50,000 species of flowering 
plants known. Walhch has 8 names for Pteris aqiiilina, 
and I do think he has two names for f of the species in the 
early part of his catalogue, besides Don's, Royle's, Edge- 
worth's, Eoxbm'gh's, and often De Candolle's. This how- 
ever is an old story. I admire yom' great caution and 
desire to curb my rabid radicalism : but the tide will turn 
one day and the reducing species will go on apace, and then 
the reaction will be terrific. After all there is something 
to be said for me. I am a rara avis, a man who makes his 
bread by specific Botany, and I feel the obstacles to my 
progress as obstacles to my way to the butcher's and baker's. 
What is all very pretty play to amateur Botanists is death 
to me. 
The following letters to Asa Gray deal with the Introduction 
to the New Zealand Flora. 
Kew : Wednesday, January 26, 1854. 
My dear Gray, — I was extremely pleased by your letter 
last night, and quite as much with the mere fact of my treating 
of the subject having been thought worthy your attention, 
as with the many too flattering things you say of it. Such 
Essays attract so little attention in this country, that one feels, 
at least I did, that I was writing for the dead more than for 
the hving, though amongst other men Agassiz had a promin- 
ent seat in judgment before me. After all I regard the whole 
Essay more as a resume of general impressions than a speci- 
men of close reasoning, for of the latter, in truth, the subject 
does not admit. There is not a single argument that will not 
cut both ways, and may not be turned fro and con species, 
specific centres, &c., &c. Your turning my arguments 
against myself on the point, that two originally created dis- 
tinct species so similar as to be almost undistinguishable, 
may exist in two \videly sundered localities, is an awful 
staggerer, and I have always felt it to be the most impractic- 
able objection of any to the possibility of determining what 
is and what is not a species. I have touched on that very 
point at ch. 2, § 2, towards end. ' These considerations; etc.,' 
but perhaps too gingerly, also in the Fl. Antarct. I think, see 
Emfctrum. I combat this theory more upon principle than 
upon facts ; — once admit it and the flood gates are opened 
