To W. D. Fox 19 March 
Down Farnborough Kent
My dear Fox
How long it is since we have had any communication & I really want to hear how the world goes with you; but my immediate object is to ask you to observe a point for me, & as I know how you are a very busy man with too much to do, I shall have a good chance of your doing what I want, as it wd be hopeless to ask a quite idle man.—
As you have a noah’s ark,1 I do not doubt that you have pigeons; (how I wish by any chance they were fantails!) Now what I want to know is, at what age nestling pigeons have their tail feathers sufficiently developed to be counted. I do not think I ever even saw a young pigeon. I am hard at work on my notes, collating & comparing them, in order in some 2 or 3 years to write a book with all the facts & arguments, which I can collect, for & versus the immutability of species.—2 I want to get the young of our domestic breeds to see how young, & to what degree, the differences appear. I must either breed myself (which is no amusement, but a horrid bore to me) the pigeons or buy them young, & before I go to a seller whom I have heard of from Yarrell,3 I am really anxious to know something about their development not to expose my excessive ignorance, & therefore be excessively liable to be cheated & gulled— With respect to the one point of the tail feathers, it is, of course, in relation to the wonderful development of tail feathers in the adult fan-tail.
If you had any breed of Poultry pure, I wd beg a chicken with exact age stated about a week or fortnight old! to be sent in Box by Post, if cd have the heart to kill one, & secondly wd let me pay postage. Indeed I shd be very glad to have a nestling common pigeon sent, for I mean to make skeletons, & have already just begun comparing wild & tame ducks,4 & I think the results rather curious, for on weighing the several bones very carefully, when perfectly cleaned, the proportional weights of the two have greatly varied; the foot of the tame having largely increased. How I wish I could get a little wild duck of a week old, but that I know is almost impossible.—
With respect to ourselves, I have not much to say: we have just now a terribly noisy house with the Hooping cough:5 but otherwise are all well. Far the greatest fact, about myself is that I have at last quite done with the everlasting Barnacles. At the end of the year we had two of our little Boys very ill with fever & Bronchites & all sorts of ailments.6 Partly for amusement & partly for change of air we went to London & took a House for a month, but it turned out a great failure, for that dreadful frost just set in when we went, & all our children got unwell & Emma & I had cougsh, & colds, & rheumatism nearly all the time.7 We had put down first on our list (of things to do) to go & see Mrs Fox, but literally, after waiting some time to see whether the weather would not improve, we had not a day when we both could go out.
I do hope before very long you will be able to manage to pay us a visit: Time is slipping away, & we are getting oldish. Do tell us about yourself & all your large family.
I know you will help me, if you can, with information about the young pigeons: & anyhow do write before very long.
My dear Fox | Your sincere old friend | C. Darwin
Amongst all sorts of odds & ends, with which I am amusing myself, I am comparing the seeds of the vars. of plants. I had formerly some wild cabbage seeds, which I gave to some one. Was it to you? It is a thousand to one that it is thrown away, if not I shd be very glad of a pinch of it.—
Asks WDF to observe at what age pigeons have tail-feathers sufficiently developed to be counted.
CD is hard at work on his notes for a book with all the facts "for & versus" the immutability of species.
Asks for a young chicken and a nestling common pigeon.
Please cite as
Darwin Correspondence Project, “Letter no. 1651,” accessed on 21 January 2017, http://www.darwinproject.ac.uk/DCP-LETT-1651