73/4. "International Horticultural Congress," London, 1866,
quoted in "Variation of Animals and Plants," Edition II., Volume
II., page 113.) What I meant in my paper on Linum about plants being
dimorphic in function alone, was that they should be divided into two
equal bodies functionally but not structurally different. I have been
much interested by what you say on seeds which adhere to the valves
being rendered conspicuous. You will see in the new edition of the
"Origin" (673/5. "Origin of Species," Edition IV., 1866, page 238. A
discussion on the origin of beauty, including the bright colours of
flowers and fruits.) why I have alluded to the beauty and bright colours
of fruit; after writing this it troubled me that I remembered to have
seen brilliantly coloured seed, and your view occurred to me. There is a
species of peony in which the inside of the pod is crimson and the seeds
dark purple. I had asked a friend to send me some of these seeds, to
see if they were covered with anything which could prove attractive to
birds. I received some seeds the day after receiving your letter, and I
must own that the fleshy covering is so thin that I can hardly believe
it would lead birds to devour them; and so it was in an analogous case
with Passiflora gracilis. How is this in the cases mentioned by you? The
whole case seems to me rather a striking one.

I wish I had heard of Mikania being a leaf-climber before your paper
was printed (673/6. See "Climbing Plants (3rd thousand, 1882), page 116.
Mikania and Mutisia both belong to the Compositae. Mikania scandens is a
twining plant: it is another species which, by its leaf-climbing habit,
supplies a transition to the tendril-climber Mutisia. F. Muller's
paper is in "Linn. Soc. Journ." IX., page 344.), for we thus get a
good gradation from M. scandens to Mutisia, with its little modified,
leaf-like tendrils.

I am glad to hear that you can confirm (but render still more wonderful)
Hackel's most interesting case of Linope. Huxley told me that he thought
the case would somehow be explained away.

LETTER 674. TO F. MULLER. Down [Received January 24th, 1867].

I have so much to thank you for that I hardly know how to begin. I have
received the bulbils of Oxalis, and your most interesting letter of
October 1st. I planted half the bulbs, and will plant the other half
in the spring. The case seems to me very curious, and until trying some
experiments in crossing I can form no conject