skip to content

Darwin Correspondence Project

From William Henry Harvey   3 January 1857

Trin. Coll. Dublin

Jan. 3d. 1857.

My dear Sir

Your letter arrived during my absence in the Country at Xmas, and I only received it on my return to town this evening. 1 In reply to your query respecting the sexes of Algæ—the great majority with whose male & female organs I am acquainted are Monoecious in the Linnæan sense—but the different sexes are frequently placed in juxta position, within the walls of a common receptacle,—much in the same way as those of Euphorbia are brought within an involucre. In most of the Fucoideæ both spores & antheridia are found in each little cyst of the receptacle [DIAGRAM HERE] — But in some Cystoseiræ & Sargassa they occur in different cysts.— And other genera are truly Diœcious, such as Splachnidium, Durvillœa, Sarcophycus, Hormosira, & some others—& many Sargassa.— Cutleria multifida is a good example of a clearly diœcious plant.

I do not remember any invariably Diœcious Rhodosperm (or Floridea)—except perhaps some of the Callithamnia may be so. They are at least polygamous. You are, of course, aware of the double female system of the Florideæ—which is invariably dioecious—but I think the male is common to either kind of female. It is perhaps more common to find antheridia on individuals bearing “tetraspores”, than on those that bear “spores”.—

I am not acquainted with any instance of true hermaphroditism, such as occurs in flowers. The nearest approach to such is found in the Fuci, & in certain Dictyoteæ & Chordarieæ—

No doubt you are familiar with Thurets admirable papers on the Sexes of the Algæ, in various Vols. of An. des Sc. Nat.2 If not, you should look to them.

I am obliged by your kind congratulations on my return home.3 I hope we may see you at the Dublin meeting of Brit. Assn. this year, & that Hooker will be here too.4

Believe me | my dear Sir | very truly yours | W. H. Harvey.

CD annotations

crossed pencil
crossed pencil
Top of first page: ‘Ch. 3.’5 pencil


CD’s letter has not been found, but see letter to J. D. Hooker, 10 December [1856], in which CD mentioned his intention to write to Harvey concerning the separation of sexes in Algae.
CD had earlier asked Joseph Dalton Hooker for a copy of Gustave Thuret’s famous paper (Thuret 1854–5) on the sexual reproduction of Algae (letter to J. D. Hooker, 21 [May 1856]).
Harvey had recently returned from a three-year visit to Ceylon and Australia, during which he had made extensive collections of Algae and other botanical and marine invertebrate specimens (Memoir of W. H. Harvey … with selections from his journal and correspondence (London, 1869), pp. 244–312).
Neither CD nor Hooker attended the Dublin meeting of the British Association for the Advancement of Science, 26 August – 2 September 1857.
A reference to chapter 3, ‘On the possibility of all organic beings occasionally crossing’, of CD’s species book (Natural selection, pp. 35–91).


Natural selection: Charles Darwin’s Natural selection: being the second part of his big species book written from 1856 to 1858. Edited by R. C. Stauffer. Cambridge: Cambridge University Press. 1975.

Thuret, Gustave Adolphe. 1854–5. Recherches sur la fecondation des Fucacées, suivies d’observations sur les anthéridies des Algues. Annales des sciences naturelles (botanique) 4th ser. 2: 197–214; 3: 5–28.


Sexes of algae.

Letter details

Letter no.
William Henry Harvey
Charles Robert Darwin
Sent from
Trinity College, Dublin
Source of text
DAR 166: 115
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 2035,” accessed on 24 November 2020,

Also published in The Correspondence of Charles Darwin, vol. 6