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Letter 2044

Doubleday, Henry to Darwin, C. R.

26 Jan 1857

    Summary Add

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    Sends specimens of Tortrix, which illustrate the extraordinary variation of markings in two or three species. In every family of Lepidoptera there seem to be species extremely prone to vary and in some localities they vary more than in others.

Transcription

Epping

Jany 26th 1857

My dear Sir,

With this you will receive a few specimens of Tortrix of which I beg your acceptance— they will illustrate the extraordinary variation of markings in two or three species—

No 1. Peronea Hastiana. (Tortrix Hastiana of Linné)—the description in the Fauna Suecica applies to the variety marked thus + —and the specimen is still in the Cabinet— This species feeds in the larva state upon the sallow and most of the varieties may be obtained from one brood of larvae—but they seem almost endless and have been considered by most of the older writers as distinct species— — I believe I was the first person in this country who felt convinced that the host of nominal species of these Buttons” as they are called, would sink into two—Hastiana and Cristana—and this <  > by everyone—

No. 2. Peronea cristana— this species is equally as variable as the last but all the varieties have a raised tuft or button on the upper varying much in size and colour—

No 3. Pœdisca sordidana— this species varies very much as you will see by the two specimens sent—

In every family of Lepidoptera there seem to be two or three species extremely prone to vary—and it is certain that in some localities they vary more than they do in others. In rearing Lepidoptera from the eggs I have frequently found that if you have a brood from a typical female of a varying species the moths will all be like the parents—

Some years ago I made some experiments with the varieties of Harpalyce RussataHaworth & Stephens described several of these varieties as distinct species— I felt convinced that they were all one and to prove it I caught several fem<ales> and obtained a numb<er> of eggs— I had bro<ods> from three typica<l> <  > of Haworth and when the moths appeared they were all exactly alike— after this I caught a female of the yellow-banded variety—the Comma-notata of Haworth—and from the eggs of this female I reared all the varieties— With the central fascia yellow—white—black—and all intermediate shades constituting the Centum-notata, Comma-notata, perfuscata &c of Stephens— —

It is singular that some species should vary so much while others closely allied should scarcely ever vary at all— species too, really distinct—often approach so closely as to be separated with difficulty in the perfect state— for instance Acronycta Psi, tridens and Cuspis— yet the larvae of these three species are totally different from each other—

Locality seems to affect the shade of colour of many species— Scotch specimens of Lepidoptera are generally much darker than those of the south of England— this is particularly the case with Aplecta occulta, Hadena adusta, Xylophasia polyodon, and Aplecta tructa.

I hope you will write again if you want any other information that it is in my power to give and with best wishes believe me | My dear Sir | Yours most sincerely | Henry Doubleday
Charles Darwin Esq

I do not want the box returned as it is of no value | H Dy

    Footnotes Add

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    f1 2044.f1
    CD had just completed chapter 4 on ‘Variation under nature’ of his species book (Natural selection, pp. 95–171). See ‘Journal’ (Appendix II).
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    f2 2044.f2
    Linnaeus 1761, p. 346. Linnaeus's collections, including his cabinet of insect specimens, had been purchased in 1784 by James Edward Smith, founder of the Linnean Society. The specimen is listed in the catalogue of the Linnean collection (Jackson 1913, p. 32).
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    f3 2044.f3
    Doubleday's chief interest was in standardising the system of nomenclature used in England with that followed by continental naturalists. Parts of his Synonymic list of British butterflies and moths appeared between 1847 and 1850, and a much more complete edition was brought out in 1859. Further supplements appeared in 1865 and 1873 (DNB).
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    f4 2044.f4
    Haworth 1803–28 and Stephens 1828–46.
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    f5 2044.f5
    See letter to Henry Doubleday, [before 5 February 1857].
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    f6 2044.f6
    A reference to chapter 4 of CD's species book. See n. 1, above.
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