PECULIAK SPECIES AND OCEANIC ISLANDS 430\ 



other causes of peculiarity, as a preponderance of species, 

 genus or higher group, or insulation of individuals, &c., 

 &c., must be secondary considerations. Except Brown and 

 Humboldt, no one has attempted this, all seem to dread the 

 making Bot. Geog. too exaict a science ; they find it far 

 easier to speculate than to employ the inductive process. 

 The first steps to tracing f.he progress of the creation of 

 vegetation is to know the jSroportion in which the groups 

 appear in different localities, and more particularly the 

 relation which exists betwee'n the floras of the localities, a 

 relation which must be expi-essed in numbers to be at all 

 tangible. 



^ Edinburgh : July 1845.i 



Bother variation, development and all such subjects ! 

 it is reasoning in a circle I believe after all. As a Botanist 

 I must be content to take spiecies as they ap'pear to he, not 

 as they are, and still less as tliiey were or ought to be. You 

 see I am annoyed at my own incapacity to fathom or follow 

 the subject to any good purjpose (open confession is good 

 for the soul). i 



I think I can give you plenty of instances of peculiar 

 genera with several good species in very small islands. [A 

 list follows.] j 



I have always felt opposed to Bory's (who is a great 

 Gascon ! but not to be despised) views of the variableness 

 of insular species. I certainly have no good evidence in 

 favour of the loose statement I Wde and which corresponded 

 with a vague idea I held, of ins'ects being scarce on islands ; 

 yet 13 species is surely very fe^ for KeeUng if size is to be 

 regarded ; how often may yoiu not find 13 on your own 

 window ? Kerguelen Land ha^i only 3. New Zealand and 

 V.D.L. are certainly poor — in tTrinidad (of Brazils) I saw 

 only 3, I think, a Hemerohius aiid the House flies and Cock- 

 roach, introduced from a wreck : Canaries and Madeira are 

 poor, I think ; Cape de Verds a^e too dependent on the W. 

 coast of Africa to judge from, j Nothing struck me as so 

 marvellous as the appearance of '4 Insecta and many Arach- 

 nida you mention as on St. Paul's rocks. Still I agree with 

 you on the main point that sucli few as there are would be 

 enough for impregnation if they <mly went to work about it. 



* For Darwin's answer, see ^ore Letters, i. 51. 



