Discusses specific varieties, especially geographic varieties.
Comments on the effects of the glacial age on the tropics.
King St Leicester
28 March 1861
My Dear Sir
I received your kind letter today & think it better to reply at once, as I am going to London on Monday for a few days study at the Insect room Brit. Mus. & shall not have another opportunity very soon. It gives me very great pleasure to find that my paper is likely to be useful to you. I am quite convinced that Insects offer better or clearer illustrations of the problems you occupy yourself with than any other class of animals or plants. It is so easy with them to obtain great series of examples & have them before you in a small compass, which is one advantage they have.—
I do not think the result I have come to regarding the persistence of the Guiano-Amazonian fauna can be shaken. I can see no traces of a migration of high-temperate-zone forms across the region. Now there are a number of genera of insects characteristic of the high-temperate zones, which are now common to S. America & N. America with Europe; but they have not a single representative in Amazonia, although some of them have representatives along the Andes of New Granada & Peru. Your hypothesis only requires (as you have stated) a migration along belts of latitude & therefore I do not think that the conclusion I have come to affects your position much after all.— I am further confirmed in my view that no migration took place across Guiano-Amazonia by the fact that there is a migration going forward now, or has been within the historic period of species of a migratory genus of Butterflies, but although one or other of the forms has obtained a footing in most other regions of the world there is no trace of them in that country. I allude to the species of the genus Pyrameis of which there are two English species P. atalanta & P. cardui. The geographical distribution of the species of this genus is very peculiar & has often excited attention. The following is a sketch of the facts
P. atalanta is found throughout Europe & N. America as far
South as Mexico. On the Southern slopes of the Himalaya, & in Madeira (!) it
exists as P. Callirhoe considered by some as a local var. In Java it
presents us with a further var. in P. Dejeanii: & in
the Sandwich Islands another allied form, P. Tammeamea; It appears to go no
further South than Java, & is not found in S. America.
Pyrameis cardui is found throughout Europe, Africa to the cape of Good hope; Asia
& the Asiatic islands to Australia & New Zealand, without
varying.— In America it is found throughout the united states, in Venezuela it
exists only as a var. P. Leachiana, throughout N. America it is found
in conjunction with P. Huntera a very closely allied species; but the two have
different areas, although existing together in some parts; To the west of the Andes from
California to chili there exists another form of Cardui, viz P. Carye; and in
the S. of Brazil another, P. Myrinna; in the Amazonian region not a
trace of any of these forms is to be found. From these facts it would appear
When I read your book first, the chapter on Geogr. distr. of course struck me very much; but a doubt occurred to me whether the resemblance in the faunas & floras between the N. & S. temperate zones was of such a nature as to require the explanation you have given. I am quite ignorant of the nature of the curious resemblance in the plants of Tierra del fuego & am quite inclined to think my doubt is unfounded in this respect.
However, two considerations have presented themselves to
The other consideration is that there are genera peculiar to the high temperate zones
of both hemispheres which present in South America compact groups of species so very
dissimilar to those of North America that it is out of the question that they could have
been derived thence so lately as the glacial period. I will give you a strong &
very intelligible case viz that of the Chilian species of Carabus, of which
yourself discovered several of extreme beauty. The genus
Carabus at the present time is not found in the Northern hemisphere, further south than
With regard to the question you ask me—whether an intermediate local form B is numerous & widely dispersed between the ranges of its extreme forms A & C: the facts that I have on the subject are numerous & rather ill digested at present. They are complicated in themselves & difficult. I know many instances of two local forms separated by a wide space without apparent natural barriers, untenanted by intermediate forms. There are many others (closely allied) which exist together on their mutual frontiers without blending. There are others which are very polymorphic in a central region, whilst in other localities E. W. N. & S. segregated into several well defined local varieties or admitted species. I will mention now one case only that meets your question. It is one, whose correctness I am quite sure of. On the dry soils, supporting for the most part a thinner forest growth, of the hilly regions of Guiana & Venezuela there exists a conspicuous Heliconia, H. Melpomene, it is abundant also in the central parts of the lower Amazons where the Hilly sandy country occurs & is found on the N. & S. Shores in extreme profusion. In the moist alluvial plains eastward to Par´a & westward to Peru & Bolivia, not a single individual is to be seen. In its place, occupying exactly the same sphere as it were, is H. Thelxiope a form so strikingly peculiar in colours that no one has ever doubted it to be a perfectly distinct species; it swarms in individuals & is nearly constant in its specific characters. Now wherever this form comes into contact with Melpomene there exists a number of intermediate varieties many of which have been described as species: they are rare, & very restricted in range. They have puzzled Lepidopterists & it has been almost settled that they were hybrids. I am convinced they are not hybrids; I never saw Melpomene & Thelxiope in copula; and besides these pretended hybrids exist at Demerara & Cayenne, where Thelxiope does not occur. I am thoroughly convinced that Thelxiope is a local variety of Melpomene, having all the appearance of a species, but created by the influences to which it has been subjected, out of Melpomene; & that the intermediate forms are the gradations. I have found Melpomene in copula with these forms & perhaps it may sometimes be so with Thelxiope, but that would not affect the case much I think.
The group from which I have supplied this example is very interesting,—being restricted to S. America, which swarms with its species; & apparently a modern creation. I am now studying it with a view to writing upon it & I think I have got a glimpse into the laboratory where Nature manufactures her new species.
—The other question you ask me relates to sexual selection.— I have seen Papilios attracted by bright colours in the forest, namely by the scarlet sepals of certain plants having inconspicuous or no flowers. I have also seen repeatedly many males following a female.— On this subject I will point out to you the following facts. In the æneas section of the genus Papilio, the males are generally of extremely brilliant colours, velvety black vivid green, carmine, & red with opalescent reflections,—the females are plainer & so different from the males that they were generally held to be distinct species until I took them in copulˆa. Now it is not all the species that present this disparity. In one P. Panthonus the two sexes are exactly alike in colours, the male only being a trifle brighter; from this species the divergence may be traced getting wider & wider from species to species up to P. Sesostris or P. Childrenæ, where the dissimilarity reaches its highest point. There is exactly the same phenomenon presented in the genus Epicalia & others. The females, however, vary in localities;—& although I thoroughly believe in your theory of sexual selection yet I think that local circumstances have some effect on colours. I do not however think that sunlight is the direct cause of vivid colours, although beautifully coloured male butterflies are almost always in the sun (genus Catagramma) whilst their drab partners are in the shade. I think the causes lie in the abundance of food, warmth & moisture of the atmosphere & even in the sluggish state of the atmosphere because the brightest coloured butterflies are not generally found within the influence of the Atlantic sea breezes, but in the sultry valleys of the Andes & the centre of the continent & these causes operate on the larva & so by correlation on the perfect insect.
I cannot say that I have noticed female butterflies pointedly selecting their male partners. The extremely rich male butterflies of the genus Catagramma live & sport together in the sun light all day, whilst their plainer coloured females are confined to the shades of the forest. The males too appear to be very much more numerous than the females,— I think there is no doubt now about this significant fact there must be many hundred males to one female of these butterflies, & in another genus Cybdelis where the males are also distinguished by rich colours the males are immensely more numerous than the females. In another beautiful genus, Megistanis no female has yet been found although the males are very numerous. In Callithea, however where the males are the most richly coloured of all butterflies, both sexes are found in equal numbers, but here the females are not much behind the males in beauty. The males which sport together all day in the sunlight disappear about 4--5 P.M. & I have watched them then flying off to the forest (towards the summits of the trees) where doubtless some of them find their mates.—
There are no strictly nocturnal Lepidoptera gaily coloured in the tropics: There is no
scarcity of brilliantly col
Perhaps the above facts will illustrate a little the problems of sexual disparity & beauty of colours. There is no phase of your theory I like better than its explanation of the subtle adaptations of organic beings. There is one topic which Entomology will help to illustrate viz. that of mimetic analogies. I have an immense number of facts on this subject. Some of these resemblances are perfectly staggering,—to me they are a source of constant wonder & thrilling delight. It seems to me as though I obtain a glimpse of an intelligent motive pervading nature, as well as of the mighty never-resting wonder working laws that regulate all things.—
—I received the copy of 3
Believe me My Dear Sir Yours sincerely | H W Bates
There is a stupid error in my paper, the note referring to ``Recent & ancient fossil shells''. The secretary took upon himself to correct the proof, I saw it and forgot to erase it—
- f1 3104.f1Letter to H. W. Bates, 26 March .
- f2 3104.f2New Granada was the name of the former Spanish colony that included present-day Colombia, Ecuador, Venezuela, and Panama.
- f3 3104.f3See Journal of researches, p. 38. CD's South American beetles were described by George Robert Waterhouse and Frederick William Hope (see Correspondence vol. 2).
- f4 3104.f4CD included Bates's information about South American Carabus species in the discussion of the mundane glacial period in the fourth edition of Origin (Origin 4th ed., p. 454).
- f5 3104.f5The vast collection of Coleoptera amassed by John Charles Bowring was formally presented to the British Museum in 1863 (British Museum (Natural History) 1904--6, 2: 581).
- f6 3104.f6Bates published these data in Bates 1861b, pp. 557--8. In describing the relationships between the various local species of Heliconidae of the Amazon valley, he referred to these forms as illustrating the `process of the creation of a new species' and `the manufacture, as it were, in process.' (Bates 1861b, p. 501).
- f7 3104.f7Bates published some of his material on mimicry in butterflies and moths in Bates 1861b, pp. 502--15, stating that the explanation of mimicry `seems to be quite clear on the theory of natural selection, as recently expounded by Mr. Darwin in the ``Origin of Species.''' (ibid., p. 511).
- f8 3104.f8Bates had first met Alfred Russel Wallace when Wallace was attending the Collegiate School in Leicester and the two went on entomological excursions together. In 1847, they decided to undertake a joint expedition to the Amazon, raising funds by offering specimen collections from little-explored areas. After four years in South America, Wallace returned to England in 1852, departing again in 1854 on an eight-year scientific expedition to the Malay Archipelago. See Marchant ed. 1916, 1: 24--36.
- f9 3104.f9The reference is to an incorrect citation in Bates 1861a, p. 226 n., of Samuel Pickworth Woodward's A manual of the Mollusca; or, a rudimentary treatise of recent and fossil shells (Woodward 1851--6).