this expression is common to all or most of the families of birds. I know
of this only in the fowl, swan, tropic-bird, owl, ruff and reeve, and
cuckoo. I fancy that I remember having seen nestling birds erect their
feathers greatly when looking into nests, as is said to be the case with
young cuckoos. I should much like to know whether nestlings do really thus
erect their feathers. I am now at work on expression in animals of all
kinds, and birds; and if you have any hints I should be very glad for them,
and you have a rich wealth of facts of all kinds. Any cases like the
following: the sheldrake pats or dances on the tidal sands to make the
sea-worms come out; and when Mr. St. John's tame sheldrakes came to ask for
their dinners they used to pat the ground, and this I should call an
expression of hunger and impatience. How about the Quagga case? (469/2.
See Letter 235, Volume I.)

I am working away as hard as I can on my book; but good heavens, how slow
my progress is.


LETTER 470. TO F.C. DONDERS.
Down, March 18th, 1871.

Very many thanks for your kind letter. I have been interested by what you
tell me about your views published in 1848, and I wish I could read your
essay. It is clear to me that you were as near as possible in preceding me
on the subject of Natural Selection.

You will find very little that is new to you in my last book; whatever
merit it may possess consists in the grouping of the facts and in
deductions from them. I am now at work on my essay on Expression. My last
book fatigued me much, and I have had much correspondence, otherwise I