Asks JD to observe Leschenaultia formosa to verify CD's hypothesis of how it is fertilised. Also suggests an experiment to determine whether it is fertilised by nocturnal insects.
Down, Bromley, Kent
I hope that you will excuse the liberty which I take in writing to you and asking you a
My belief is that insects in creeping in to suck the copious nectar brush open the indusium, and the hairs of their abdomens stir up the pollen and push it down on to the stigmatic surface. I find that this easily effected by a camel-hair brush. Now what I want to beg is for you to have the great kindness to watch for a short time the Leschenaultia and see whether Bees visit it; and if they do, to endeavour to observe whether in crawling in or whilst sucking, they do not open the lips of the indusium. As this plant may be visited by nocturnal insects, it would be a very interesting experiment to cover over with bag on frame made of very open gauze one or two plants (plucking off any open flowers) and then see whether they seed at all or less freely than plants left to the visits of insects.—
This may appear a trifling enquiry to you; but the subject has been largely discussed
by R. Brown, Aug: St. Hilaire and other celebrated
Botanists; and D
I hope that you will excuse the liberty I take in begging this favour and | I remain, Dear Sir | Your obliged Servant | Charles Darwin
- f1 2803.f1Drummond was superintendent of the government botanic gardens of Western Australia (R. Desmond 1977).
- f2 2803.f2For Drummond's reply, see the letter from James Drummond, 17 September 1860.
- f3 2803.f3CD had conducted similar experiments to ascertain the role of insects in facilitating the pollination of clover and kidney-beans, the results of which are recorded in his Experimental book (DAR 157a). See also Correspondence vol. 6, letter to Gardeners' Chronicle, 18 October .
- f4 2803.f4Robert Brown and Augustin Fran¸cois C´esar Prouven˜cal de Saint-Hilaire. CD refers to Brown 1814, pp. 559--60, and to Saint-Hilaire 1841, pp. 572--3, in which the fertilisation of Goodenia (a plant closely related to Leschenaultia) is discussed. The passage in Saint-Hilaire 1841 is marked in CD's copy of the work (Darwin Library--CUL).