My dear Hooker

Would you be so kind as to send me a line to say whether you shall be up in London, on next Thursday, Friday or Saturday,, & if you are naturally coming up, will you appoint some hour & day at some place & I will be there: I am anxious to know at once whether you will be up, as I have appointments to make for all these days & cannot do so, till I hear from you.—

I believe Arthrobalanus has no ovisac at all!, & that the appearance of one is entirely owing to the splitting, & tucking up to the posterior penis, of the inner membrane of sack.— I have just found a Cirripede with an indisputably abortive anterior penis; so that this chief anomalous feature (viz two penes) in Arthro-balanus is in some degree brought within bounds.—

Ever yours | C. Darwin

The alteration in my microscope, in accordance with your advice, has really been beyond value: the porcupine quills better than the glass tubes; the Chutney Sauce capital, so that I have many daily memorials of you.

N.B. I have cleverly invented two blocks of wood to support my wrists when dissecting under microscope a splendid invention.

Adios.—