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Darwin Correspondence Project

From Hubert Airy   21 July 1872

13. Eliot Place. | Blackheath. S.E.

1872. July 21.

My dear Sir

I am afraid I made a bad mistake in my letter yesterday, in saying that the leaf belonging to the topmost node in grass-stems is obsolete. On examination I see that the leaf is fully developed; and I hope you will obliterate that passage from my letter.1

With this, I send one or two lilac twigs, which present a characteristic series of variations from the normal 2-whorl, in illustration of the ‘nodal’ question.2

I could also show you an oak-twig affecting a succession of 3-whorls with long internodes from whorl to whorl; as a specimen of variation from the alternate towards the verticillate arrangement.3

I am, my dear Sir, | Yours very truly | Hubert Airy

Footnotes

In Airy 1874, pp. 304, Airy discussed variability of the number of leaf-ranks in the same species, giving as an example whorls of three being produced by plants like lilacs that usually bear whorls of two. The ‘nodal’ question relates to Airy’s view that the node had no independent importance and existed only as the starting point of the leaves (see letter from Hubert Airy, 20 July 1872 and n. 1).
The variation in oak showing the alternate going to a verticillate (or whorled) arrangement involved an increase from one leaf per node to three per node.

Bibliography

Airy, Hubert. 1874. On leaf-arrangement. Abstract. Communicated by Charles Darwin. [Read 30 April 1874.] Proceedings of the Royal Society of London 22 (1873–4): 298–307.

Summary

Corrects a factual error in his previous letter [8418].

Sends specimens illustrative of the "nodal" question.

Letter details

Letter no.
DCP-LETT-8422
From
Hubert Airy
To
Charles Robert Darwin
Sent from
Blackheath
Source of text
DAR 159: 19
Physical description
2pp

Please cite as

Darwin Correspondence Project, “Letter no. 8422,” accessed on 16 October 2019, https://www.darwinproject.ac.uk/letter/DCP-LETT-8422.xml

Also published in The Correspondence of Charles Darwin, vol. 20

letter