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 should have written to you long ago, as I often intended to
tell you in how high a degree your essay published in Beale's Archives
interested me. (470/1. Beale's "Archives of Medicine," Volume V., 1870.)
I have heard others express their admiration at the complete manner in
which you have treated the subject. Your confirmation of Sir C. Bell's
rather loose statement has been of paramount importance for my work.
(470/2. On the contraction of the muscles surrounding the eye. See
"Expression of the Emotions," page 158. See Letters 464, 465.) You told
me that I might make further enquiries from you.

When a person is lost in meditation his eyes often appear as if fixed
on a distant object (470/3. The appearance is due to divergence of the
lines of vision produced by muscular relaxation. See "Expression of the
Emotions," Edition II., page 239.), and the lower eyelids may be seen to
contract and become wrinkled. I suppose the idea is