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Darwin Correspondence Project

From William Ogle   23 July 1876

10 Gordon St. | Gordon Square

July 23. 1876.

My dear Mr. Darwin

I need hardly say that I shall feel much pleased if you can make any use of the small fact noticed by me concerning Monkshood. I fear however that I can give you but very scanty details.1

In 1871 I was in a part of Switzerland where there was great abundance of blue Aconitum Napellus, with a sprinkling also of white specimens of the same species. I chanced one day to notice that all the blossoms from white specimen which I was examining had a hole made through the corolla for the theft of nectar, while the blossoms of a blue specimen which I was comparing with the white one had not been similarly mistreated.

Thinking that this difference of treatment might account for the difference in the abundance of the two varieties, I collected and examined a hundred racemes of each variety.

Not a single fully opened blossom on the 100 white specimens was without the nibbled hole; while not a single blossom on the 100 blue specimens had it.2 One or two however of the blue blossoms had been gnawed irregularly by some animal or other, probably a slug or snail.

I do not know whether the Aconitum is sterile, when insects are excluded.3

I wish I could give you more information, but this is all I have.

I am reminded by this question of colour of a passage which I noted some year or two ago in Mead on the Plague, written some 140 years ago, and thought would interest you as bearing on the correlation of colour and disease. “I am well aware that there are plagues among animals, which do not indifferently affect all kinds of them, some being confined to a particular species (like the disease of the Black Cattle here, a few years since, which neither proved infectious to other brutes nor to men;) yet it has always been observed that the true plague among men has been destructive to all Creatures of what kind soever”4

Believe me | Yrs. very sincerely | W. Ogle.


CD added Ogle’s observations to Cross and self fertilisation, pp. 427–8.
In Cross and self fertilisation p. 428, CD argued that since the flowers of Aconitum napellus were strongly proterandrous (the anthers open long before the stigma becomes receptive), the plant would be more or less sterile without insect aid (see letter to William Ogle, 22 July [1876] and n. 4).
Ogle quotes from Richard Mead’s Discourse on the plague (Mead 1744, p. 88). Ogle may have misinterpreted Mead’s statement somewhat, since ‘black cattle’ was used as a general term in the early eighteenth century, when most domestic cattle were black (Youatt 1834, p. 257).


Cross and self fertilisation: The effects of cross and self fertilisation in the vegetable kingdom. By Charles Darwin. London: John Murray. 1876.

Mead, Richard. 1744. A discourse on the plague. 9th edition. London: A. Miller and J. Brindley.

Youatt, William. 1834. Cattle: their breeds, management, and diseases. London: Baldwin and Cradock.


Recounts his observations on the different ways bees perforate flowers of white and blue varieties of monkshood. [See Cross and self-fertilisation, p 428.]

Letter details

Letter no.
William Ogle
Charles Robert Darwin
Sent from
London, Gordon St, 10
Source of text
DAR 77: 164–5
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10565,” accessed on 24 September 2021,

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