From J. D. Hooker 28 December 1860
Kew
Dec 28 /60
Dear Darwin
Your notes about the little Compos. are very interesting indeed—1 I would certainly send them to G. C. which will woodcut the illustration—2 The case is a great extension of the well-known fact, that many Compositæ (the common groundsel is one)3 have a layer of vesicles full of mucus on the achænium, which swell & burst when wet—& so hold down the seed to ground, but I know of no case like this, of the mucus cells being developed only on the lower sides of the oblique Achænium—4 This side is the outer as respects the position of the floret in the capitulum, & it is a curious fact that various other Compos: with erect (or but slightly inclined) achænia have a similar glandular development on the outer surface only—& especially such as inhabit S. Africa— The Selection principle comes in here capitally— The laws of growth render all the achænia in most capitula of comp. lop sided, especially such comps. as have the outermost flowers female (the case with all these). in falling it is the lop-side that touches the ground, & the most glandular that adhere best & hence grow &c &c &c.5
The same phenomena occur in seeds (not seed vessels as in Compos.) of Cruciferæ, & it is curious that that genus of Crucif. in which the viscid coat is thickest is Australian. I have followed the subject a little in Crucif.— Some Crucif. you know have dehiscent fruit: others indehiscent: I find the mucous coat general in the dehiscent—never in the indehiscent.—but some genera have upper half of capsule indehiscent, lower dehiscent. in these all the seeds are mucous, or all not mucous.— this is only inteligeable on Nat. Select. principle & shews that the simple physiolog. peculiarity of testa is more permanent than structure of Capsule.— this further falls in with my principle of classification of the Order— What is more odd is that the mucous or dry testa is a more constant character than form & direction of Embryo! I did want to write a good paper on whole subject in reference to classification & origin of genera & species too in order Cruciferæ, but have not strength of mind for it.6
You ask how my Book on plants brews?7—as flat as beer with bad malt.— I have no Torula cerevisiæ 8 in me any more.— I have arrived at a hale old age & shall take care of it. & am seriously thinking of taking out a commission of Lunacy against my one hard working friend Huxley— I feel all sorts of inward monitors advising me against over excitement or9
CD annotations
CD note:11
Footnotes
Bibliography
Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.
Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.
Natural selection: Charles Darwin’s Natural selection: being the second part of his big species book written from 1856 to 1858. Edited by R. C. Stauffer. Cambridge: Cambridge University Press. 1975.
Summary
CD’s article worth publishing in Gardeners’ Chronicle. JDH interprets CD’s observation in terms of selection. Has observed similar phenomenon in Cruciferae, where it can be taxonomically important.
Letter details
- Letter no.
- DCP-LETT-3033
- From
- Joseph Dalton Hooker
- To
- Charles Robert Darwin
- Sent from
- Kew
- Source of text
- DAR 100: 143–4, 146–8
- Physical description
- AL inc †, CD note, 3 CD sketches
Please cite as
Darwin Correspondence Project, “Letter no. 3033,” accessed on 29 March 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-3033.xml
Also published in The Correspondence of Charles Darwin, vol. 8