Has been invited to lecture at the Royal Institution by Spottiswoode. Discusses subjects he might deal with and his reasons for attempting it.

Tells of a complicated case of a double sale of a living.

Huxley says F. M. Balfour passed brilliantly.

Advice to GHD on whether to accept invitation to lecture at the Royal Institution.

Murray has sent the Quarterly Review issue. CD has told Murray that he is convinced Mivart is the author and what he thinks of him.

Sends index [of Descent, 2d ed.] with instructions for proof-reading.

Asks GHD questions about heat transmission; he wants to use it as an analogy to illustrate transmission of motor impulses through leaves of Dionaea.

GHD explains conduction, radiation, and convection.

His paper on political economy for Royal Institution lecture has reached 60 pages. Plans to send it to Contemporary Review.

Writes about instructions to compositor and return of proofs [of Descent]. Requests return of 2d volume of Descent, to which he may want to refer.

Thanks GHD for clear lecture on heat.

Will keep paper on proportion of sexes, in case GHD wants it again.

Wants him to translate some pages of Swedish or Norwegian sent by A. W. Malm, "a good man".

Glad to see the statistical paper ["Theory of exchange value", Fortn. Rev. n.s. 17 (1875): 243–53].

GHD has been using E. Norman [CD’s copyist], and he apologises if this has caused delays to CD’s work.

Mainly family news.

Eager to read GHD’s political economy MS "though Heaven knows whether I shall understand it".

Spottiswoode is pressing for an answer to invitation to GHD to lecture at the Royal Institution. GHD is having MS of the paper he has written sent to CD, so that CD can advise whether he should accept the invitation.

Sends Murray’s report of November sales of CD’s books. "I am well content."

CD thinks better of "cousin paper" than GHD does.

With respect to GHD’s "viscous work", remembers endless discussions of movement of viscous matter 20 years back, apropos of movement of glaciers.

Appleton will bring out the new edition of Descent in the U. S., so GHD’s work will now be in three editions.

Has finished the "cousin paper" and will offer it to W. Farr for the Statistical Society.

Describes other work in progress.

Has CD heard of A. M. Mayer’s curious work on audition of insects [Am. J. Sci. 3d ser. 8 (1874): 89–103?]

Returns historical sketch [of GHD’s "cousin paper"?] with comments. "For Heavens sake put a sentence in some conspicuous place that your results seem to indicate that consanguineous marriage, as far as insanity is concerned, cannot be injurious in any very high degree."

Regrets the trouble GHD has had.

Letter [to editor of Contemp. Rev.] saying that W. D. Whitney would like to reply to Max Müller. Hopes space can be given him.

J. T. Knowles [editor of Contemp. Rev.] hopes W. D. Whitney’s article will be a long one.

CD is sorry about GHD’s account of his low spirits. "I know well the feeling of life being objectless & all being vanity of vanities."

CD recounts events of the April-fool’s day séance at Hensleigh [Wedgwood]’s. Asks GHD to find out whether Sidgwick’s account of it agrees with what he has heard. "What rubbish the whole does seem to be!"

Sends errata for Insectivorous plants 2d printing.

Errata for Insectivorous plants, 3d printing.