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To C. H. Blackley   9 March 1877

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Mar 9. 1877

Dear Sir

I am much obliged for your essay which I have read with interest.1 Your calculation of the weight of pollen grains is wonderful.2 It might be worth your while to look at p. 376 & p. 405 of my “Effects of cross & self-fertilization” where I give the number of pollen-grains produced by some few plants. Typha, which is an anemophalous species, is said to yield 144 grains weight of pollen—3

The preparations of the leaves of Drosera shew the structure of the glands with admirable clearness—4

I remain dear Sir | yours faithfully | Ch. Darwin

Footnotes

1
An offprint of Blackley’s paper ‘New observations on hay-fever, with new experiments on the quantity of ozone in the atmosphere’ is in DAR 136: 9; delivered in 1876, it was published in 1879 under the title ‘On the methods and the instruments used in investigating the causes of hay-fever’ together with the discussion of the paper before the British Homoepathic Society (Blackley 1879).
2
In Blackley 1879, pp. 129–31, a method was described for determining the weight of pollen-grains using a balance, microscope, and specially made apparatus. Blackley used this data to determine the weight of pollen required to bring on an attack of hay fever. On p. 133, he cited some of CD’s comments on Blackley 1873 (see Correspondence vol. 21, letter to C. H. Blackley, 5 July [1873]).
3
In Cross and self fertilisation, pp. 376–7, CD referred to Blackley’s experiments showing that more pollen was released by the anthers in dry conditions than wet (Blackley 1873), and cited other authors who had estimated the number of pollen-grains produced by the dandelion, the peony, Wistaria sinensis, and hibiscus. On pp. 405–6, CD gave the weight of pollen produced by a bulrush plant (Typha latifolia), and referred to Blackley’s experiments showing that there were many more pollen-grains in the higher atmosphere than the lower. CD made notes for this reply on the back of his offprint of Blackley 1879, which is now in DAR 136: 9.
4
The nature of the preparations has not been identified, but for Blackley’s interest in Drosera (the genus of sundews), see the letter from C. H. Blackley, 18 June 1877. Blackley was interested in CD’s experiments showing the very small amounts of substances that induced physiological action in Drosera, as supporting evidence for his own research on the very small amounts of pollen that could cause hay fever; see Blackley 1882, pp. 608–9.

Bibliography

Blackley, Charles Harrison. 1873. Experimental researches on the causes and nature of catarrhus æstivus (hay-fever or hay-asthma). London: Bailliere, Tindall & Cox.

Blackley, Charles Harrison. 1879. On the methods and the instruments used in investigating the causes of hay-fever, with new experiments on the weight of pollen necessary to bring on the disorder, and new observations on the action of ozone. Annals and Transactions of the British Homoeopathic Society 8: 118–34.

Blackley, Charles Harrison. 1882. On the influence of infinitesimal quantities in inducing physiological action. Monthly Homœopathic Review 26: 604–18.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

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

Summary

Thanks for CHB’s essay [New observations on hay-fever (1877?)]. The calculation of the weight of pollen-grains is wonderful. Suggests he consult Cross and self-fertilisation, pp. 376, 405 for information on this subject.

Letter details

Letter no.
DCP-LETT-10886
From
Charles Robert Darwin
To
Charles Harrison Blackley
Sent from
Down
Source of text
Yale University Medical Historical Library, Harvey Cushing / John Hay Whitney Medical Library (MMS)
Physical description
LS 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 10886,” accessed on 26 September 2022, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-10886.xml

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