148 THE WRITING OF THE 'ORIGIN OF SPECIES.' [1859. 



we do, and must, differ widely on several heads. Lastly, I 

 should like particularly to know whether I have taken any- 

 thing from you, which you would like to retain for first publi- 

 cation ; but I think I have chiefly taken from your published 

 works, and, though I have several times, in this chapter and 

 elsewhere, acknowledged your assistance, I am aware that it 

 is not possible for me in the Abstract to do it sufficiently.* 

 But again let me say that you must not offer to read it if very 

 irksome. It is long about ninety pages, I expect, v/hen 

 fully copied out. 



I hope you are all well. Moor Park has done me some good. 

 Yours affectionately, 



C. DARWIN. 



P.S. Heaven forgive me, here is another question : How 

 far am I right in supposing that with plants, the most import- 

 ant characters for main divisions are embryological ? The 

 seed itself cannot be considered as such, I suppose, nor the 

 albumen, &c. But I suppose the cotyledons and their posi- 

 tion, and the position of the plumule and the radicle, and the 

 position and form of the whole embryo in the seed are 

 embryological, and how far are these very important ? I wish 

 to instance plants as a case of high importance of embryo- 

 logical characters in classification. In the Animal Kingdom 

 there is, of course, no doubt of this. 



C. Darwin to J. D. Hooker. 



Down, March $th [1859]. 

 MY DEAR HOOKER, Many thanks about the seed . . . 

 it is curious. Petrels at St. Kilda apparently being fed by 



* " I never did pick any one's much do I owe to your writings and 



pocket, but whilst writing my pre- conversation, so much more than 



sent chapter I keep on feeling (even mere acknowledgments show." 



when differing most from you) just Letter to Sir J. D. Hooker, 1859. 

 as if I were stealing from you, so 



