To J. D. Hooker 1 November 
My dear Hooker
You may believe how deeply your letter has interested me. How very very kind you are, busy as you are, to give up so much time to me.—1
Since I wrote I have traced bundles to superior (so called) sepal, anther & rostellum all to one bundle most clearly; & in a confluent stigma two bundles to 2 lower sepals; so homologies of this part now clear & certain. I am uneasy at not understanding why R. Brown did not trace the vessels longitudinally; he clearly expresses this view of Rostellum & stigma, but gives no evidence.—2
I have examined several other very simple Labellums, & the vessels always run as stated: Anthers with pollen have been seen on Labellum of Bee Ophrys; I will try at a thick Labellum for the missing bundle, but doubt success; it is so difficult when object opake I must take thick longitudinal slice & soak in nitric acid. Many of your hints will be most useful: I will study your letter over & over again.—
If you really can spare another Catasetum, when nearly ready, I shall be most grateful: had I not better send for it? The case is truly marvellous; the (so-called) sensation or stimulus from a light touch is certainly transmitted through the antennæ for more than 1 inch, through at least 73 cells, instantaneously; & a membrane is ruptured (as in Listera) & double elasticity comes into play & pollinia are shot out with sticky gland always foremost.3 A cursed insect or something let my last flower off last night!— Another very young spike is coming forward. But there are many trials which I should wish to make. It is singular that left-hand antenna always guards a distinct part of Labellum from the right-hand antenna.
Many of the orchids sent today are extremely valuable to me.— I would have given 5£ for the Dendrobium macrophyllum.— I think I understand partly Acropera: the pollinia when exposed for short time to air shrink much in thickness & can then be inserted into stigma; on insect flying they would rapidly be dried: I should rob your hot-house; but 2 or 3 more flowers would settle this enigma: Is labellum uppermost? I think I partly understand how rostellum must be touched to withdraw the pollinia—4
I shall be very curious to hear how Labellum of Bolbophyllum moves.5 Is not Barberry & Cactus opposed to compound organs being irritable? Lateral lobes of Labellum of Listera cordata seemed covered with glands; but I did not see interest & did not observe carefully: [corners] in Spiranthes glandular.
Jamieson makes great use & thinks most highly of your Glacial-Himalayan work.—6
If you do really send me another Catasetum could I keep it in my greenhouse by keeping up fire night & day: we can raise it to 70o— The gardener who keeps present plant, says he has formerly found that Catasetum does not require very great Heat.—7
I have not seen Bonatea, but in drawings Labellum looks almost divided. Never mind about Hedyotis: Asa Gray is going to send me living plants of one of the same Rubiaceous group:8 he seems wonderfully interested in the Primula case. Rhamnus lanceolatus seems another case. Can you tell me best nursery to apply to for rare trees as this Rhamnus or plants as Verbascum.
Believe me I appreciate your wonderful kindness—
Yours affectionately | C. Darwin
I have lately read heaps of letters between Mr Jamieson & Lyell;9 & I 〈 〉
If Labellum of Bulbophyllum closes up to column when touched (in middle?) & you can tell me what angle it makes with column before being touched, I will have drawing made.—
P.S. I send Catasetum to be named.— I think I have made out mechanism of Dendrobium macrophyllum, in whatever position flower stands, unless it hangs almost perpendicularly downwards, with Labellum downwards. It is a frightful evil that I cannot see my way till I have examined so many specimens.
Sensitive responses in Catasetum.
Acropera becoming clear.
T. F. Jamieson impressed by JDH’s work on Himalayan glaciers.
Please cite as
Darwin Correspondence Project, “Letter no. 3305,” accessed on 28 July 2016, http://www.darwinproject.ac.uk/DCP-LETT-3305