380 BOTANY [CHAP. XI 



Letter 701 within the staminal tube. 1 One can see that if there is to be 

 a split in the tube, the law of symmetry would lead it to 

 be double, and so free one stamen. Your view, if confirmed, 

 would be extremely well worth publication before the Linnean 

 Society. It is to me delightful to see what appears a mere 

 morphological character found to be of use. It pleases me 

 the more as Carl Nageli has lately been pitching into me 

 on this head. Hooker, with whom I discussed the subject, 

 maintained that uses would be found for lots more structures, 

 and cheered me by throwing my own orchids into my teeth. 2 



All that you say about changed position of the peduncle 

 in bud, in flower, and in seed, 3 is quite new to me, and reminds 

 me of analogous cases with tendrils. This is well worth 

 working out, and I dare say the brush of the stigma. 



With respect to the hairs or filaments (about which I once 

 spoke) within different parts of flowers, I have a splendid 

 Tacsonia with perfectly pendent flowers, and there is only 

 a microscopical vestige of the corona of coloured filaments ; 

 whilst in most common passion-flowers the flowers stand 

 upright, and there is the splendid corona which apparently 

 would catch pollen. 4 



On the lower side of corolla of foxglove there are some 

 fine hairs, but these seem of not the least use 5 a mere 

 purposeless exaggeration of down on outside as I conclude 

 after watching the bees at work, and afterwards covering 

 up some plants ; for the protected flowers rarely set any seed, 

 so that the hairy lower part of corolla does not come into 



1 It seems that Darwin did not know that the staminal tube in the 

 diadelphous Leguminosas serves as a nectar-holder, and this is surprising, 

 as Sprengel was aware of the fact. 



2 See Letters 697-700. 



3 See Vochting, Bewegung der Bin then und Friichte, 1882 ; also 

 Kerner, Pflanzenleben> Vol. I., p. 494, Vol. II., p. 121. 



4 Sprengel (Entdeckte Geheimniss, p. 164) imagined that the crown 

 of the Passion-flower served as a nectar-guide and as a platform for 

 insects, while other rings of filaments served to keep rain from the nectar. 

 F. Mtiller, quoted in H. Miiller {Fertilisation, p. 268), looks at the crowns 

 of hairs, ridges in some species, etc., as gratings serving to imprison 

 flies which attract the fertilising humming-birds. There is, we believe, no 

 evidence that the corona catches pollen. See Letter 704, note 3. 



5 It has been suggested that the hairs serve as a ladder for humble 

 bees ; also that they serve to keep out " unbidden guests." 



