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Darwin Correspondence Project

From W. E. Darwin   [April–May 1865]1



My Dear Father,

I enclose Camera outlines of the 3 sorts of pollen. I think the pollen of the red Longstyled & of the yellow Longstyled are as nearly of the same size as anything can be.2

The only difference I can see is that the Red Longstyled have a good many more sterile than the Y. Long S. and they are much more markedly sterile. If you would send me some more flowers of the 2 kinds, I would make outlines more carefully of the sterile-looking ones, & try & see roughly the comparative proportions in each, that is to say if it would be any use.

I find Rhamnus will not be in flower till well into May.3

We have still got this heavenly weather, & everything has come slick into leaf in the last 4 days  

I should like to hear what Horace thinks of School.4

Your affect son | W E Darwin


The date is established by the reference to Horace Darwin being at school (see n. 4, below), and by the reference to Rhamnus catharticus not flowering until well into May (see n. 3, below).
CD was investigating the relationship between primroses, cowslips, and oxlips. His experiments on crossing the different forms of these plants were designed to show whether they were varieties descended from a common parent or distinct species; CD published his conclusions in ‘Specific difference in Primula. William drew the pollen of these plants using a camera lucida attached to his microscope; he probably refers to red and yellow cowslips.
CD had been eager to see specimens of Rhamnus catharticus (a synonym of R. cathartica (buckthorn)) in 1864 to determine whether the male and female flowers had different stylar forms (see Correpondence vol. 12, letter from H. E. Darwin to W. E. Darwin, [18 May 1864]). William, however, had failed to obtain any from the Isle of Wight that year (see this volume, Supplement, letter from W. E. Darwin, 18 June [1864]); CD probably asked William to collect some during the flowering season in 1865.
Horace Darwin went to Clapham Grammar School in spring 1865 after Emma had consulted his private tutor, George Varenne Reed, curate of Hayes, Kent (letter from Emma Darwin to H. E. Darwin, [25 March 1865] (DAR 219.9: 23); Emma Darwin’s diary (DAR 242)). Prior to this, Horace had been so ill for three years that he was able to study for only short periods with Reed (Correspondence vol. 11, letter from G. V. Reed, 12 January 1863 and nn. 2 and 3).


‘Specific difference in Primula’: On the specific difference between Primula veris, Brit. Fl. (var. officinalis of Linn.), P. vulgaris, Brit. Fl. (var. acaulis, Linn.), and P. elatior, Jacq.; and on the hybrid nature of the common oxlip. With supplementary remarks on naturally produced hybrids in the genus Verbascum. By Charles Darwin. [Read 19 March 1868.] Journal of the Linnean Society (Botany) 10 (1869): 437–54.


Sends camera outlines of pollen. Thinks the red longstyled ones are more sterile than the yellow.

Letter details

Letter no.
William Erasmus Darwin
Charles Robert Darwin
Sent from
Source of text
Cornford Family Papers (DAR 275: 20)
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 4506F,” accessed on 27 May 2022,

Also published in The Correspondence of Charles Darwin, vol. 24 (Supplement)