Ɛpsilon

To Víctor López-Seoane   27 December 1881

Down, | Beckenham, Kent.

Dec 27. 1881

Dear Sir,

It would be a pleasure to me to assist you in your researches, but I cannot give the desired information, as I have not specially attended to the embryology of the Vertebrata.1 I strongly advise you to procure F. Balfour’s ‘Comparative Embryology’ in 2 volumes, which contains many original observations with full references to all that has been published on the subject, together with many illustrations.2 I believe it to be the most valuable biological work which has been published for very many years. It will soon be translated into German, and I believe into French.

I have received your Essays, but just lately I have been so much engaged that I have not yet read them, but hope soon to do so.3

With respect to species, I quite agree with you that it is a serious evil to load our books with new names. Nevertheless the description, as a variety, of any constant difference, however small, between two forms, seems to me highly advisable.

As far as I can judge there is no rule about giving a new name to a form, excepting that of its differences being of an important nature. Whenever two forms are connected by intermediate varieties, it seems best to give the whole series a single name, however different the extremes may be; and I followed this plan in describing the Cirripedia.4

I am delighted at the revival of Science in Spain, and with all good wishes, I remain Dear | Sir Yours faithfully | Charles Darwin

LS(A)

2
Francis Maitland Balfour published the second volume of A treatise on comparative embryology (Balfour 1880–1) in July 1881 (see letter to F. M. Balfour, 6 July 1881).
4
CD’s systematic works on barnacles, both living and fossil, had been an outgrowth of a project on comparative anatomy (see Correspondence vol. 4). The works are notable for CD’s reduction of the proliferation of genera and species, as well as the inclusion of fossil species; moreover, his insistence on integrating material on the anatomy, habits, and geographical range into his formal descriptions was a departure from the usual relegation of such features to the appendixes (Fossil Cirripedia (1851), Fossil Cirripedia (1854), Living Cirripedia (1851), Living Cirripedia (1854)). For more on CD’s approach to systematics, see ‘Living and fossil Cirripedia’ (www.darwinproject.ac.uk/living-and-fossil-cirripedia (accessed 19 October 2020)).

Manuscript Alterations and Comments

5.2 Dear] added in CD’s hand

Please cite as “DCP-LETT-13582A,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-13582A