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Darwin Correspondence Project

From Fritz Müller   16 January 1872

Itajahy, Sa Catharina, Brazil

January 16. 1872.

My dear Sir.

I must beg your pardon for having delayed so long answering your kind letter of Aug. 2d and expressing my cordial thanks for your having sent me a copy of Mr. Chauncey Wright’s very able refutation of Mr. Mivart’s “Genesis of species”.—1 But I have been away from my home for about five weeks on an excursion through the northern part of our province.2

The yellow, white and red Hedychium, mentioned in a former letter, are, as you suppose, distinct species.3

I have no objection to your alluding to my idea of sexual selection having come into play in the case of mimetic butterflies.4 I may here mention a curious fact relating to the same subject, which I observed a fortnight ago. On an excursion, which I made with a friend of mine, we saw two similarly coloured butterflies playing together, whirling round and pursuing each other for a considerable time. At last we succeeded in catching both of them and found, to your great surprise, that they belonged to two widely different species. I had caught the very common Agraulis Juno Cr. and my friend the rare Marpesia Petreus Cr.—5 The shape of the wings and the distribution of the colours is so different and the two butterflies were so close together for a long time, that they could hardly have mistaken each other for specimens of their own species. Apparently they were playing together only in order to behold and admire each other. Unfortunately I forgot to ascertain the sex of the two specimens.—

On the same occasion we observed three species of the curious genus Castnia, one of them (A.) being extremely frequent. The hind-wings in two of these species had dull colours; and in these, when at rest, the hind-wings were always overlapped and concealed by the front-wings. In the third species (B)

[DIAG HERE]6

the black-hind-wings were spotted with red and white, and this species, when at rest, expanded their wings horizontally, so that the hind-wings were fully exposed to view.— You know, that the Castniæ fly about, with great rapidity, during the day.—

I have of late been attending to our Termites. They are very curious animals and the several species differ much in their habits. The most interesting fact, I hitherto observed, is the existence, in some species of Calotermes, of larvæ provided with wing-like horizontally expanded processes on the prothorax and mesothorax.— The species

[DIAG HERE]78

of Calotermes do not build nests; they have but one form of neuters (soldiers, but no labourers); the fertilized females do not swell to so enormous a volume, as they do in the genus Termes. All this seems to prove, that they are a more primitive form of the family. And indeed, according to Hagen, the oldest fossil remains of Termites (Calotermes Heerii) appear to belong to that genus, which is perhaps the oldest of all now living genera of insects.9 The young larvæ provided with the curious processes live under exactly the same conditions with the older ones, in which these processes have disappeared, while the rudiments of the wings make their appearance on the mesothorax and metathorax, and thus it is not probable, that they should have acquired the processes by natural selection; it appears to be more probable, that they inherited them from a very remote ancestor, which in its adult state may have resembled these larvæ. In this case the Calotermes-larvæ might be the oldest of all known forms of insects.—

You know, that some ants (Odontomachus) use their long mandibles for making most surprising jumps in a backward direction.10 Is it not a curious coincidence, that the soldiers of some Termites have the same habit of leaping backward with the aid of their mandibles? These leaping soldiers have been described and figured by Hagen under the name of Termes cingulatus, but I have some doubts, whether they really belong to that genus.11 Linné already knew the leaping of Termites, for he says of his T. fatale: “maxillis longis altissime resiliens”;12 but no subsequent observer appears to have seen it.—

Have you already seen the Dentalium-like cases of one of our caddish-worms, (Leptocerus(?) Grumicha Vall.)?13 They show, that there may exist strange resemblances even without mimicry or analogous variation.

I hope, dear Sir, that this letter will find you in good health and am, as always, with sincere respect | Yours very faithfully | Fritz Müller.

CD annotations

1.1 I must … province. 1.5] crossed red crayon
3.1 I have … mimetic butterflies. 3.2] double scored red crayon
3.3 On an excursion … two specimens.— 3.12] crossed red crayon

Footnotes

See Correspondence vol. 19, letter to Fritz Müller, 2 August [1871]. Müller refers to Wright 1871a and to St George Jackson Mivart and Mivart 1871a.
In a letter to his brother Hermann Müller, dated 11 January 1872, Müller mentioned his trip to Doña Francisca from 11 November until 12 December 1871 (Möller ed. 1915–21, 2: 201). Doña Francisca was a German colony, founded in 1851, lying between the Sierra do Mar and the coast in the province of Santa Catarina. The main settlement was the city of Joinville, about seventy-five miles north of Müller’s home in Itajahy (Columbia gazetteer of the world).
See Correspondence vol. 19, letter to Fritz Müller, 2 August [1871] and n. 8. In his letter of 14 June 1871 (ibid.), Müller had mentioned the preference of some butterflies for red flowers of Hedychium and other genera.
See Correspondence vol. 19, letter to Fritz Müller, 2 August [1871]. CD had proposed adding a sentence to the second edition of Descent describing Müller’s speculations on the possible role of sexual selection in butterfly mimicry; in fact, he did not add the sentence.
Agraulis juno is now Dione juno; Marpesia petreus is the ruddy daggerwing butterfly.
Wing A has been identified as belonging to a specimen of Synpalamides phalaris; wing B belongs to a specimen of Imara pallasia (identifications made by John Chainey of the Natural History Museum, London); the wings are glued to the original letter. Both species belong to the moth family Castniidae and have in the past been classified within Castnia (for a complete synonymy for these species, see Lamas 1995, p. 78).
Müller probably added the question mark following Calotermes rugosus (now Rugitermes rugosus) not because he was uncertain of his identification of the species, but because he did not know the source of the name. It was first described by Hermann August Hagen in Hagen 1858, p. 63.
Calotermes nodulosus is now Rugitermes nodulosus.
Hagen had named the fossil Calotermus heerii (Hagen 1858, pp. 73–4); it is now Mastotermes heerii.
Odontomachus is the genus of trap-jaw ants. For more on their use of mandibles for jumping, see Patek et al. 2006.
Termes cingulatus is now Aparatermes cingulatus. For Hagen’s description of their use of mandibles for jumping, see Hagen 1858, p. 190 and plate I, fig. 13.
See Linnaeus 1758–9, 1: 609.
Dentalium is the genus of tusk shells (marine scaphopod molluscs), so named because in shape they resemble a tusk or canine tooth. Leptocerus is a genus of long-horn caddisflies. The caddisfly species to which Müller refers was originally named Phryganea grumicha (see Vallot 1855, p. xii), but was transferred to the genus Leptocerus by Hagen, based on the structure of the larval cases (Hagen 1864, pp. 226–7). Hagen was misled by the fact that some leptocerid larvae use the empty cases of this species (see Flint et al. 1999, p. 81). The species is now Grumicha grumicha.

Summary

Has no objection to CD’s alluding to FM’s idea that sexual selection has come into play in mimetic butterflies.

Reports observations on other butterflies and on termites.

Letter details

Letter no.
DCP-LETT-8161
From
Johann Friedrich Theodor (Fritz) Müller
To
Charles Robert Darwin
Sent from
Santa Catharina, Brazil
Source of text
DAR 142: 55
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 8161,” accessed on 26 June 2017, http://www.darwinproject.ac.uk/DCP-LETT-8161

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

letter