The History of a Forty Years' Friendship. 20 1 
have no other connection, except in their first letter.” 1 In 1853 
Hooker published his famous Introductory Essay to the Flora of 
New Zealand. The clear statement of his position in regard to 
species is particularly interesting in view of the frequent interchange 
of ideas with Darwin during the preceding decade. Hooker wrote, 
“ Although in this Flora I have proceeded on the assumption that 
species, however they originated or were created, have been handed 
down to us as such, and that all the individuals of a unisexual plant 
have proceeded from one individual, and all of a bisexual from a 
single pair, I wish it to be distinctly understood that 1 do not put 
this forward intending it to be interpreted into an avowal of the 
adoption of a fixed or unalterable opinion on my part.” 2 This 
section of the Essay concludes as follows :—“ I cannot conclude this 
part of the subject better than by adopting the words of the most 
able of transatlantic botanists, who is no less sound as a generaliser 
than profound in his knowledge of details. ‘ All classification and 
system in Natural History rest upon the fundamental idea of the 
original creation of certain forms which have naturally been per¬ 
petuated unchanged, or with such changes only as we may conceive 
or prove to have arisen from varying physical influences, accidental 
circumstances or from cultivation.’” In the margin of his copy of 
the Essay Darwin expressed his opinion of Asa Gray’s views by a 
single mark of exclamation. 3 
The following footnote by Hooker 4 illustrates the strong influence 
exerted by his friend at this period. “Mr. Darwin not only directed 
my earliest studies in the subject of the distribution and variation 
of species, but has discussed with me all the arguments, and drawn 
my attention to many of the facts which I have endeavoured to 
illustrate in this essay. I know of no other way in which I can 
acknowledge the extent of my obligation to him than by adding that 
I should never have taken up the subject in its present form, but for 
the advantages I have derived from his friendship and encourage¬ 
ment.” In his Address as President of the Geographical section of 
the British Association meeting at York in 1881, Hooker said, in 
reference to Geographical distribution, “As Humboldt was its 
1 Ibid, p. 31. 
1 Introductory Essay to The Flora of New Zealand, p. viii. Flora 
of New Zealand, Vol. I, 1853. 
3 The library of Charles Darwin, through the kindness of Dr. 
Francis Darwin, is now housed in the Cambridge Botany 
School. (Catalogues of the Library of Charles Darwin, Cambridge, 
1908). 
4 Introductory Essay, p. xxii. 
