To August Weismann 1 and 4 May 1875
Down, Beckenham, Kent
May 1st. 1875
My dear Sir
I did not receive your essay for some days after your very kind letter, and I read German so slowly that I have only just finished it.1 Your work has interested me greatly, and your conclusions seem well established. I have long felt much curiosity about Season-dimorphism, but never could form any theory on the subject. Undoubtedly your view is very important, as bearing on the general question of variability.2 When I wrote the Origin I could not find any facts which proved the direct action of climate and other external conditions.3 I long ago thought that the time would soon come when the causes of variation would be fully discussed, and no one has done so much as you in this important subject. The recent evidence of the difference between birds of the same species in the N. and S. United States well shows the power of climate.4 The two sexes of some few birds are there differently modified by climate, and I have introduced this fact in the last edition of my Descent of Man. I am, therefore, fully prepared to admit the justness of your criticism on sexual selection of Lepidoptera; but considering the display of their beauty, I am not yet inclined to think that I am altogether in error.5
What you say about reversion being excited by various causes, agrees with what I concluded with respect to the remarkable effects of crossing two breeds; namely that anything which disturbs the constitution leads to reversion, or, as I put the case under my hypothesis of pangenesis, gives a good chance of latent gemmules developing.6 Your essay, in my opinion is an admirable one, and I thank you for the interest which it has afforded me.
With much respect | I remain, my dear Sir | Yours very faithfully | Charles Darwin
P.S.— I find that there are several points, which I have forgotten. Mr. Jenner Weir has not published anything more about caterpillars, but I have written to him, asking him whether he has tried any more experiments, and will keep back this letter till I receive his answer.—7 Mr. Riley of the U. States supports Mr. Weir, and you will find reference to him and other papers at p. 426 of the new and much corrected Edit. of my Descent of Man.8 As I have a duplicate copy of Vol. I (I believe 2nd. Vol. is not yet published in German) I send it to you by this post.9 Mr. Belt in his “Travels in Nicaragua”, gives several striking cases of conspicuously coloured animals (but not caterpillars) which are distasteful to birds of prey: he is an excellent observer and his book, “The Naturalist in Nicaragua”, very interesting.10
I am very much obliged for your photograph which I am particularly glad to possess, and I send mine in return.11
I see you allude to Hilgendorf’s statements, which I was sorry to see disputed by some good German observer. Mr. Hyatt, an excellent palæontologist of the U. States, visited the place and likewise assured me that Hilgendorf was quite mistaken.12
I am grieved to hear that your eye-sight still continues bad, but anyhow it has forced your excellent work in your last essay.13
May 4th.
Here is what Mr. Weir says.
“In reply to your enquiry of Saturday I regret that I have little to add to my two communications to the Entomol. Soc. Transactions.
I repeated the experiments with gaudy caterpillars for years, and always with the same results, not on a single occasion did I find richly coloured, conspicuous larvæ eaten by birds. It was more remarkable to observe that the birds paid not the slightest attention to gaudy caterpillars, not even when in motion— the experiments so thoroughly satisfied my mind that I have now given up making them”.14
Footnotes
Bibliography
Allen, Joel Asaph. 1871. On the mammals and winter birds of East Florida, with an examination of certain assumed specific characters in birds, and a sketch of the bird-faunæ of Eastern North America. Bulletin of the Museum of Comparative Zoölogy 2 (1870–1): 161–450.
Descent 2d ed.: The descent of man, and selection in relation to sex. By Charles Darwin. 2d edition. London: John Murray. 1874.
Gould, Stephen Jay. 2002. The structure of evolutionary theory. Cambridge, Mass.; London: Belknap Press of Harvard University Press.
Hilgendorf, Franz. 1866. Ueber Planorbis multiformis im Steinheimer Süswasserkalk. Monatsberichte der Königlich Preussischen Akademie der Wissenschaften zu Berlin (1866): 474–504.
Hyatt, Alpheus. 1880. The genesis of the Tertiary species of Planorbis at Steinheim. Boston: Boston Society of Natural History.
Origin 6th ed.: The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. 6th edition, with additions and corrections. By Charles Darwin. London: John Murray. 1872.
Petrunkevitch, Alexander. 1963. August Weismann. Personal reminiscences. Journal of the History of Medicine and Allied Sciences 18: 20–35.
Riley, Charles Valentine. 1869–77. Annual reports on the noxious, beneficial, and other, insects of the State of Missouri. Jefferson City, Mo.: Regan & Edwards, public printer [and others].
Variation 2d ed.: The variation of animals and plants under domestication. By Charles Darwin. 2d edition. 2 vols. London: John Murray. 1875.
Weir, John Jenner. 1869. On insects and insectivorous birds; and especially on the relation between the colour and the edibility of Lepidoptera and their larvae. [Read 1 March 1869.] Transactions of the Entomological Society of London (1869): 21–6.
Weir, John Jenner. 1870. Further observations on the relation between the colour and the edibility of Lepidoptera and their larvae. [Read 4 July 1870.] Transactions of the Entomological Society of London (1870): 337–9.
Weismann, August. 1872. Ueber den Einfluss der Isolirung auf die Artbildung. Leipzig: Wilhelm Engelmann.
Summary
Comments on AW’s work [Studien zur Descendenz-Theorie, vol. 1 (1875)].
On seasonal dimorphism in Lepidoptera in relation to sexual selection.
Discusses evolutionary reversion.
Comments on birds’ avoiding brightly coloured caterpillars. Offers references on subject.
Alpheus Hyatt says Franz Hilgendorf mistaken [about Planorbis multiformis].
Quotes from letter from J. J. Weir on birds’ rejection of brightly-coloured caterpillars.
Letter details
- Letter no.
- DCP-LETT-9965
- From
- Charles Robert Darwin
- To
- Leopold Friedrich August (August) Weismann
- Sent from
- Down
- Source of text
- DAR 148: 344
- Physical description
- C 4pp
Please cite as
Darwin Correspondence Project, “Letter no. 9965,” accessed on 24 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-9965.xml
Also published in The Correspondence of Charles Darwin, vol. 23