I thank you very truly for your intended present, and I am sure that your book will interest me greatly.

I am delighted that you have taken up the very difficult and most interesting subject of the habits of insects, on which Englishmen have done so little.

How incomparably more valuable are such researches than the mere description of a thousand species! I daresay you have thought of experimenting on the mental powers of the spiders by fixing their trap-doors open in different ways and at different angles, and observing what they will do.
We have been here some days, and intend staying some weeks; for I was quite worn out with work, and cannot be idle at home.
I sincerely hope that your health is not worse.
LETTER 252.

TO A.HYATT.
(252/1.

The correspondence with Professor Hyatt, of Boston, U.S., originated in the reference to his and Professor Cope's theories of acceleration and retardation, inserted in the sixth edition of the "Origin," page 149.
Mr.Darwin, on receiving from Mr.Hyatt a copy of his "Fossil Cephalopods of the Museum of Comparative Zoology.