18431862] ORCHIDS 271 



just been looking at Lindley's list in the Vegetable Kingdom, Letter 600 

 and I cannot resist one or two of his great division of 

 Arethuseae, which includes Vanilla. And as I know so well 

 the Ophreae, I should like (God forgive me) any one of the 

 Satyriadae, Disidae and Corycidae. 



I fear my long lucubrations will have wearied you, but it 

 has amused me to write, so forgive me. 



To J. D. Hooker. Letter 601 



Part of the following letter is published in the Life and Letters, the 

 remainder, with the omission of part bearing on the Glen Roy problem, 

 is now given as an example of the varied botanical assistance Darwin 

 received from Sir Joseph Hooker. For the part relating to Verbascum 

 see the Variation of Animals and Plants, Ed. II., 1875, Vol. II., p. 83. 

 The point is that the white and yellow flowered plants which occur in two 

 species of Verbascum are undoubted varieties, yet " the sterility which 

 results from the crossing of the differently coloured varieties of the same 

 species is fully as great as that which occurs in many cases when distinct 

 species are crossed." 



The sterility of the long-styled form (B) of Linum grandiflorum, with 

 its own pollen is described in Forms of Flowers, Ed. II., p. 87 : his con- 

 clusions on the short-styled form (A) differ from those in the present letter. 



Sept. 28th [1861]. 



I am going to beg for help, and I will explain why I 

 want it. 



You offer Cypripedimn ; I should be very glad of a speci- 

 men, and of any good-sized Vandeae, or indeed any orchids, 

 for this reason : I never thought of publishing separately, and 

 therefore did not keep specimens in spirits, and now I should 

 be very glad of a few woodcuts to illustrate my few remarks 

 on exotic orchids. If you can send me any, send them by 

 post in a tin canister on middle of day of Saturday, Oct. 5th, 

 for Sowerby will be here. 



Secondly : Have you any white and yellow varieties of 

 Verbascum which you cculd give me, or propagate for me, 

 or lend me for a year ? I have resolved to try Gartner's 

 wonderful and repeated statement, that pollen of white and 

 yellow varieties, whether used on the varieties or on distinct 

 species, has different potency. I do not think any experiment 

 can be more important on the origin of species ; for if he is 

 correct we certainly have what Huxley calls new physiological 

 species arising. I should require several species of Verbascum 



