skip to content

Darwin Correspondence Project

From Thomas Meehan   3 March 1873

Germantown, Pa.,

March 3 1873

Ch. Darwin Esqr

My Dear Sir

My good neighbour Mr. Joseph Rosengarten wrote to me last Summer that you had expressed a wish to have Photographs of myself and Prof. Cope, and he very kindly enclosed two of yours, which I need not say both Prof. Cope and myself highly value. I returned mine at once to Mr. Rosengarten, and I suppose you have received it. At the time Prof. Cope was with a Government expedition to Wyoming, and has only recently returned. His Photograph also exhibits one of his discoveries of which he is very proud.1

I was very much pleased to learn from your letter a few years ago that the occasional observations I am able to make interest you.2 They give me pleasure to make them, and I never forget while enjoying this study, how much I owe to you as in a great measure the instigator of the line of thought. I only feel sorry sometimes in this account, that while aiding as I think my observations do, the facts of a continuous evolution of species and genera, I cannot feel that natural selection is an adequate cause,— nor do I feel satisfied with Prof. Copes law of acceleration and retardation as developed in his origin of Genera.3 Indeed when I see how vast is the change in plants by a simple cohesion of parts in plants,—and how easily this co-hesion is affected by mere powers of nutrition—especially in Orchidaceæ, I cannot see any genera at all in nature, so far as plants are concerned, whatever the zoologist may do. Feeling my inability to be satisfied as yet of any theory of Evolution, I am contenting myself with the position of an original observer, recording whatever seems true, and which fact sometimes helps one side as well as another.

In my paper on the laws of sex, read at the Salem meeting of the American Association,— and a paper at the Troy meeting on nutrition and sex, I incidentally referred to the association of high color with the male sex in plants.4 I have since made many more observations on the same subject, showing that with a decline in vigor (vitality) there is an appreciation of high colour, and with that high color, a gradual decline of the female characteristic of flowers, and an assumption of male ones.

If you have an opportunity of watching the growth of Delachampsia Roezeliana,5 you may perhaps get an idea of what I mean. I try to carry the idea of color as explained by you and Mr. Wallace with my observations;6 but they do not seem to fit exactly. In a year or so I may report— I fear not this, as I am arranging for a trip of some seven thousand miles through this great country the coming summer.

I mail you a paper of mine you may not have seen, in “Old and New” on sex.7 It is not intended for Scientific people, hence, is not written as I would in other events.

Very truly yours Thos. Meehan


Joseph George Rosengarten was an acquaintance of the Darwin family, perhaps introduced to them by Herbert Spencer (Proceedings of the American Philosophical Society 60 (1921): ix). For Edward Drinker Cope’s palaeontological expedition to the Bridger Basin and Washakie Basin areas of Wyoming in 1872 to 1873, see Osborn 1931, pp. 177–94; neither of the enclosed photographs has been found, but the photograph of Cope was probably that taken with a fossil specimen of Loxolophodon cornutus discovered during that expedition (Osborn 1831, plate opposite p. 584) and reproduced on p. 102.
CD’s letter has not been found; Meehan had sent CD a number of his publications in 1871 (see Correspondence vol. 19, letter from Thomas Meehan, 10 February 1871 and n. 1).
In his early work on the origin of genera (Cope 1868, Cope 1869), Cope argued that although new species could arise within a genus through the modification of existing characteristics by means of natural selection, new genera could only arise through the acquisition of new characteristics or loss of existing ones. Following Ernst Haeckel, he believed that the developmental stages of a juvenile individual reflected the stages in development of adult ancestral forms; according to Cope, individuals that passed quickly through those stages were better able to acquire new characteristics and pass these on to their offspring, whereas those with retarded development might not transmit all the characteristics of their ancestors. For more on the background and development of Cope’s ideas, see S. J. Gould 1977, pp. 85–96. CD’s annotated copy of Cope 1868 is in the Darwin Library–CUL; he referred to it in Origin 6th ed., p. 149. CD thought Cope’s theories on genera mistaken (see Correspondence vol. 19, letter to W. E. Darwin, [after 11 November 1871], and Correspondence vol. 20, letter to Alpheus Hyatt, 10 October [1872]; see also Bowler 1977, pp. 250–1).
In his paper ‘On the sexes of plants’, read at Salem, Massachusetts, Meehan reported his observations that in monoecious plants, undernourishment encouraged the production of male flowers, and in hermaphrodite plants, such as roses, camellias, and peaches, resulted in brighter coloured petals and variegated leaves (Meehan 1869, p. 259). In a paper on the influence of nutrition on sex in Castanea americana (sweet chestnut), read at Troy, New York, he similarly reported an increased tendency for undernourished plants to produce yellow leaves (Meehan 1870, pp. 283–4). CD had discussed colour in plants as one characteristic affected by differing conditions of life, such as soil type and climate, in Variation 2: 271–82.
Dalechampia roezliana is a synonym of D. spathulata; D. spathulata is in the family Euphorbiaceae and has brightly coloured bracts.
CD had discussed the possible relationship between colour and health in plants in Variation 2: 335–9, and discussed the prevalence of brighter colours in males in many species of animals, birds, and insects extensively in Descent. Alfred Russel Wallace had published a number of papers on protective coloration in butterflies and animals (see for example A. R. Wallace 1864 and [A. R. Wallace] 1867b), and had put forward a different theory from CD’s to explain brighter colouring in male birds (A. R. Wallace 1867a).
In ‘Sexual science’ (Meehan 1872a), Meehan addressed ‘the great woman question’ concluding, based on observations of other organisms, that the proper role of men was to provide for and protect women, who, however, possessed greater vitality. The copy sent to CD has not been found. Old and New was a popular literary and current affairs journal published monthly in Boston.


Bowler, Peter John. 1977. Edward Drinker Cope and the changing structure of evolutionary theory. Isis 68: 249–65.

Cope, Edward Drinker. 1868. On the origin of genera. Proceedings of the Academy of Natural Sciences of Philadelphia (1868): 242–300.

Cope, Edward Drinker. 1869. On the origin of genera. Philadelphia: Merrihew & Son, printers.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 26 vols to date. Cambridge: Cambridge University Press. 1985–.

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

Gould, Stephen Jay. 1977. Ontogeny and phylogeny. Cambridge, Mass.; London: Belknap Press of Harvard University Press.

Meehan, Thomas. 1869. On the sexes of plants. Proceedings of the American Association for the Advancement of Science (1869): 256–60.

Meehan, Thomas. 1870. On two classes of male flowers in Castanea, and the influence of nutrition on sex. Proceedings of the American Association for the Advancement of Science (1870): 282–4.

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.

Osborn, Henry Fairfield. 1931. Cope, master naturalist: the life and letters of Edward Drinker Cope, with a bibliography of his writings. Princeton: Princeton University Press. London: H. Milford. Oxford: Oxford University Press.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


Although he believes in evolution, TM feels that natural selection is an inadequate cause;

nor is he satisfied with E. D. Cope’s law of acceleration and retardation.

Discusses some of his work relating to nutrition and sex and colour and sex.

Letter details

Letter no.
Thomas Meehan
Charles Robert Darwin
Sent from
Gardeners’ Monthly , Germantown, Pa.
Source of text
DAR 171: 109
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8796,” accessed on 7 December 2019,

Also published in The Correspondence of Charles Darwin, vol. 21