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Darwin Correspondence Project

From A. W. Bennett   7 December 1876

6, Park Village East, | Regent’s Park, | N.W.


My dear Sir

I have again to thank you for your kindness in directing a copy of your new work on Fertilisation to be forwarded to me. I have at present only been able to skim it, but shall read it carefully with the greatest interest.1

A fact came under my notice this autumn with regard to the fertilisation of the maize which I do not see alluded to, & which may interest you. In the Valley of the Arve in Savoy I noticed (the first week in September) that in many or most of the maize-fields the male flowers had been cut off from the whole field except one corner. The object of this was stated to be to strengthen the plants; but, from the fact of one corner of the field being always left uncastrated, it struck me that it must be an unconscious acknowledgement of the superiority of cross- over self-fertilisation, & that the mutilation must probably be effected before the anthers are ripe.2 I did not observe the same anywhere in Switzerland (I was no further south than Savoy); but an American gentleman on the diligence told me it was customary in that country. If the fact is not a familiar one, can it be ascertained from American botanists?

Have you ever observed the relationship between the typical form of Centaurea nigra, & the rayed form (C. nigrescens Jacq.) the flowers of which closely resemble those of C. Scabiosa? When in the Isle of Wight this summer, it struck me that the rayed form, which is probably more attractive to insects, is gradually, but not very slowly, supplanting the typical form; it seems to me that while 20 years ago it was comparatively scarce, it is now the pervalent form in the South of England; it certainly is in the western part of the Isle of Wight. I do not know whether other botanists would confirm this observation or not; but if correct, will it not supply the instance for which the opponents of evolution so often challenge us, of the gradual change of species in Nature under our eyes? It would be very interesting to ascertain whether the offspring from seed of the typical C. nigra manifest a tendency to become transmuted into C. nigrescens.3

I am about to undertake a 2nd. edition of Sachs’s “Textbook of Botany” for the Clarendon Press, Oxford, as the 1st. edition is likely to be exhausted in the course of next year. Any suggestions for the improvement of the text or notes would be gratefully received—4

Pray excuse the length of this letter, & believe me | very truly yrs. | Alfred W. Bennett

C. Darwin Esq


Bennett’s name appears on CD’s presentation list for Cross and self fertilisation (see Appendix III).
Savoy, in south-east France, is part of the Western Alps and borders on Switzerland and Italy. CD’s experiments with Zea mays confirmed that crossed plants were taller than those that were self-fertilised (Cross and self fertilisation, pp. 234–5).
Centaurea nigra is common knapweed. Bennett probably refers to C. nigrescens Gren. & Godr., a synonym of C. jacea (brown-ray knapweed), which is a separate species, not a variety of C. nigra. Centaurea scabiosa is greater knapweed.
Bennett had translated Julius Sachs’s textbook of botany into English based on the third German edition with some additions from the fourth (Sachs 1873, 1874, 1875a). The second English edition was published in 1882 (Sachs 1882); the additional material added is outlined in the translator’s preface on p. vii.


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


Thanks for copy of Cross and self-fertilisation.

Reports instances of cross-fertilisation in maize,

and succession of forms of flowers on Isle of Wight.

Asks CD’s suggestions for his second edition of Julius von Sachs’s Text-book of botany.

Letter details

Letter no.
Alfred William Bennett
Charles Robert Darwin
Sent from
London, Park Village East, 6
Source of text
DAR 160: 145
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10703,” accessed on 4 December 2021,

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