1 866.] NAGELI ON SPECIES. 51 



pamphlet before printing my new edition.* On one or two 

 points, I think, you have a little misunderstood me, though I 

 dare say I have not been cautious in expressing myself. The 

 remark which has struck me most, is that on the position of 

 the leaves not having been acquired through natural selection, 

 from not being of any special importance to the plant. I 

 well remember being formerly troubled by an analogous 

 difficulty, namely, the position of the ovules, their anatropous 

 condition, &c. It was owing to forgetfulness that I did not 

 notice this difficulty in the 'Origin.' Although I can offer 

 no explanation of such facts, and only hope to see that they 

 may be explained, yet I hardly see how they support the 

 doctrine of some law of necessary development, for it is not 

 clear to me that a plant, with its leaves placed at some 

 particular angle, or with its ovules in some particular position, 

 thus stands higher than another plant. But I must apologise 

 for troubling you with these remarks. 



As I much wish to possess your photograph, I take the 

 liberty of enclosing my own, and with sincere respect I remain, 

 dear Sir, 



Yours faithfully, 



CH. DARWIN. 



[I give a few extracts from letters of various dates showing 

 my father's interest, alluded to in the last letter, in the pro- 

 blem of the arrangement of the leaves on the stems of plants. 

 It may be added that Professor Schwendener of Berlin has 

 successfully attacked the question in his ' Mechanische Theorie 

 der Blattstellungen,' 1878. 



To Dr. Falconer. 



August 26 [1863]. 



" Do you remember telling me that I ought to study 

 Phyllotaxy ? well I have often wished you at the bottom of 



* Nageli's Essay is noticed in the 5th edition. 



E 2 



