My dear Professor Donders

In about 10 days from the present date I expect to receive proofs of the first sheets of my book on Expression.

Since receiving your very generous offer of looking over any part which referred to Physiology, I have often reflected on the subject; but I still feel great difficulty in deciding what parts would be thus most benefited, as there are so many references to Physiology.¹

I also feel some doubt whether the later chapters would be intelligible to any one who had not read or skimmed over the earlier ones— On the other hand it is out of the question to expect you to look through all the sheets; more especially as the book is certainly not an important one— The Printers calculate that the M.S will cover 370–380 pages of the size & type of my Descent of Man.² So I must trust to chance in escaping error; but I will consult you if I feel doubts about special points: Yet I fear that a man is most apt to fall into error exactly where from his ignorance he feels no doubts. The chapter which I thought most dangerous, viz that on weeping was read over in M.S. some time ago by M^r Bowman; so I feel pretty safe about this Chapter.³

In y^r. last letter you said that you sh^d. probably come to England in July; & in this case I most sincerely hope that you will come & dine & sleep at Down; I shall then have the real pleasure of thanking you in person for the assistance which you have given me, which has been of the greatest value—

I do not know whether you will stay in London with M^r Bowman; but if so & you can persuade him to accompany you to Down it will give us great pleasure—⁴

M^rs Darwin begs to be very kindly remembered to you. Believe me | Yours very sincerely & obliged | Charles Darwin—