riting my P.S. I have
read the part on the influence of the nervous system on the nutrition of
parts in your last edition of Paget's "Lectures." (472/1. "Lectures on
Surgical Pathology," Edition III., revised by Professor Turner, 1870.)
I had not read before this part in this edition, and I see how foolish I
was. But still, I should be extremely grateful for any hint or
evidence of the influence of mental attention on the capillary or
local circulation of the skin, or of any part to which the mind may be
intently and long directed. For instance, if thinking intently about a
local eruption on the skin (not on the face, for shame might possibly
intervene) caused it temporarily to redden, or thinking of a tumour
caused it to throb, independently of increased heart action.

LETTER 473. TO HUBERT AIRY.

(473/1. Dr. Airy had written to Mr. Darwin on April 3rd:--

"With regard to the loss of voluntary movement of the ears in man and
monkey, may I ask if you do not think it might have been caused, as it
is certainly compensated, by the facility and quickness in turning the
head, possessed by them in virtue of their more erect stature, and the
freedom of the atlanto-axial articulation? (in birds the same end is
gained by the length and flexibility of the neck.) The importance, in
case of danger, of bringing the eyes to help the ears would call for a
quick turn of the head whenever a new sound was heard, and so would tend
to make superfluous any special means of moving the ears, except in the
case of quadrupeds and the like, that have great trouble (comparatively
speaking) in making a horizontal turn of the head--can only do it by a
slow bend of the whole neck." (473/2. We are indebted to Dr. Airy for
furnishing us with a copy of his letter to Mr. Darwin, the original of
which had been mislaid.)

Down, April 5th [1871].

I am greatly obliged for your letter. Your idea about the easy turning
of the head instead of the ears themselves strikes me as very good, and
quite new to me, and I will keep it in mind; but I fear that there are
some cases opposed to the notion.

If I remember right the hedgehog has very human ears, but birds support
your view, though lizards are opposed to it.

Several persons have pointed out my error about the platysma. (473/3.
The error in question occurs on page 19 of the "Descent of Man," Edition
I., where it is stated that the Platysma myoides cannot be voluntarily
brought into action. In the "