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Darwin Correspondence Project

To George Maw   31 August [1861]1

Down. | Bromley. | Kent. S.E.

Aug. 31st

Dear Sir

I write merely to say how grateful I shall feel for any facts on correlation or criticisms.— Will you sometime please explain a little more fully about the contracted corolla of the Pelargonium with the narrow leaves.—2

You put the difficult case of correlated changes in structure at Birth in a very striking manner. Such cases of correlation, however, interest me less than that of the Pelargonium: for according to my notions, (whether false or true) if the period of gestation became from any cause (& it does vary) shorter, if the milk did not flow, the inheritance of the new variation would be stopped by the death of the progeny; & thus a bond of apparent correlation might arise: but, I presume that no one will doubt that the case of the pelargonium is due to petals & leaves being homologous & similar at a very early period & being similarly affected by some unknown cause.—3

Cases of old or injured females assuming male attributes is perhaps even more curious than the effects of castration on males.—

I shall be truly glad to hear any facts, when you have leisure & inclination to write to me & I beg leave to remain | Dear Sir | Yours sincerely | Charles Darwin


Dated by the endorsement and by the relationship to the letter to George Maw, 19 July [1861].


Would welcome any facts on correlation, or GM’s criticisms. Explains how natural selection could produce apparent correlation of characters, but feels GM’s Pelargonium example must arise from the leaves and petals being similarly affected at an early stage by an unknown cause.

Letter details

Letter no.
Charles Robert Darwin
George Maw
Sent from
Source of text
Royal Horticultural Society, Lindley Library (MAW/1/7)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 3239,” accessed on 21 September 2020,

Also published in The Correspondence of Charles Darwin, vol. 9