PECULIAR SPECIES AND OCEANIC ISLANDS 439 



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 exact a science ; they find it far 

 easier to speculate than to employ the inductive process. 

 The first steps to tracing the progress of the creation of 

 vegetation is to know the proportion in which the groups 

 appear in different localities, and more particularly the 

 relation which exists between the floras of the localities, a 

 relation which must be expressed in numbers to be at all 

 tangible. 



Edinburgh : July 1845. 1 



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 species as they appear to be, not 

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

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

 the subject to any good purpose (open confession is good 

 for the soul). 



I think I can give you plenty of instances of peculiar 

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

 list follows.] 



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 made and which corresponded 

 with a vague idea I held, of insects being scarce on islands ; 

 yet 13 species is surely very few for Keeling if size is to be 

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

 window ? Kerguelen Land has only 3. New Zealand and 

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

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

 roach, introduced from a wreck : Canaries and Madeira are 

 poor, I think ; Cape de Verds are too dependent on the W. 

 coast of Africa to judge from. 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 such few as there are would be 

 enough for impregnation if they only went to work about it. 



1 For Darwin's answer, see More Letters, i. 51. 



