To B. D. Walsh 17 February [1868]
Down. | Bromley. | Kent. S.E.
Feb. 17th
My dear Sir
I stupidly wrote to you a few days ago before I had looked through your papers with reference to sexual differences.1 I now find heaps of facts & reasoning,—the very dim recollection of which made me write.— I write now simply, if in time, to save you the trouble of answering my letter, for a week or two, by which time I may have more questions to ask!— But I may ask some now, & if you do not receive another letter in a week’s time, I shd be most grateful if you will write to me.—
I do not know the genera Gomphus & Hæterina (see Proc. Ent. Soc. Phil. Oct. 1863 p. 223, & p. 239): are these more allied to Ephemera or Libellula;2 but what I want to know most is whether the males & females differ conspicuously in colour, & whether males are more brilliant to our eyes than the females.
You say (p. 239) in the group vulgatissimus of Gomphus that the males are much more numerous than females;3 whilst in two closely allied species viz G. fluvialis & amnicola the females are 2 or 3 times as numerous as males.4 Now I want especially to hear how the sexes differ in these two last species, relatively to the sexual differences in the vulgatissimus group; & relatively to the general type of colouring of the genus. This will be of very great interest to me.— I have just been quoting long passage from you in Pract. Ent. on aids to seizing females chiefly in Coleoptera.5
In Papilio machaon sexes alike, in many species of Papilio I believe, the sexes are very different in colour: now can you tell me anything about inequality in number of sexes in the cases in which the sexes differ & do not differ in colour: you will see at once at what I am driving.
In Papilio Turnus & Argynnis Diana, are the males or females the most abundant.?6
Pray forgive me troubling you & begging all these favours—
Yours very truly | C. Darwin
I do not think I shall have anything more to write at present so shd. be extremely obliged for an answer whenever you can spare time.
Footnotes
Bibliography
Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.
Summary
Has looked through BDW’s papers and finds heaps of facts on sexual differences. Asks questions on sexual differences in particular species.
Letter details
- Letter no.
- DCP-LETT-5883
- From
- Charles Robert Darwin
- To
- Benjamin Dann Walsh
- Sent from
- Down
- Postmark
- Feb 17 68
- Source of text
- Field Museum of Natural History, Chicago (Walsh 12A)
- Physical description
- ALS 4pp
Please cite as
Darwin Correspondence Project, “Letter no. 5883,” accessed on 28 March 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-5883.xml
Also published in The Correspondence of Charles Darwin, vol. 16