18441858] ALPINE VARIETIES 47 



together. I am really ashamed to think of your having Letter 16 

 given me such a valuable work ; all I can say is that I 

 appreciate your present in two ways as your gift, and for 

 its great use to my species-work. I am very glad to hear 

 that you mean to attack this subject some day. I wonder 

 whether we shall ever be public combatants ; anyhow, I 

 congratulate myself in a most unfair advantage of you, viz., 

 in having extracted more facts and views from you than from 

 any one other person. I daresay your explanation of poly- 

 morphism on volcanic islands may be the right one ; the 

 reason I am curious about it is, the fact of the birds on the 

 Galapagos being in several instances very fine-run species 

 that is, in comparing them, not so much one with another, as 

 with their analogues from the continent. I have somehow 

 felt, like you, that an alpine form of a plant is not a true 

 variety ; and yet I cannot admit that the simple fact of the 

 cause being assignable ought to prevent its being called a 

 variety ; every variation must have some cause, so that the 

 difference would rest on our knowledge in being able or not 

 to assign the cause. Do you consider that a true variety 

 should be produced by causes acting through the parent ? But 

 even taking this definition, are you sure that alpine forms 

 are not inherited from one, two, or three generations ? Now, 

 would not this be a curious and valuable experiment, 1 viz., to 

 get seeds of some alpine plant, a little more hairy, etc., etc., than 

 its lowland fellow, and raise seedlings at Kew : if this has not 

 been done, could you not get it done ? Have you anybody 

 in Scotland from whom you could get the seeds ? 



I have been interested by your remarks on Senecio and 

 Gnaphalium : would it not be worth while (I should be very 

 curious to hear the result) to make a short list of the generally 

 considered variable or polymorphous genera, as Rosa, Salix, 

 Rubus, etc., etc., and reflect whether such genera are generally 

 mundane, and more especially whether they have distinct or 

 identical (or closely allied) species in their different and 

 distant habitats, 



Don't forget me, if you ever stumble on cases of the same 

 species being more or less variable in different countries. 



1 For an account of work of this character, see papers by G. Bonnier 

 in the Revue Generate, Vol. II., 1890; Ann. Sc. Nat., Vol. XX. ; Revue 

 Generate, Vol. VII. 



