Corrects chemical concentrations CD has been using [in insectivorous plant experimentation].

Thinks highly of GHD’s article [probably "On beneficial restrictions to liberty of marriage", Contemp. Rev. 22 (1873): 412–26]. A good omen for the future.

Writes for CD to thank RS for his very valuable information.

Criticises CD’s letter to Nature ["Complemental males in certain cirripedes", Collected papers 2: 177–82].

On the elimination of useless parts.

GHD fails to see the point of CD’s use of the law of distribution about a mean.

Discusses his health following a visit to Dr C[lark?]. Has made an appointment for CD.

Sends CD a draft of a letter to Nature [see 9087], which he thinks expresses CD’s meaning.

CD thinks GHD’s letter is an excellent clarification [of CD’s conjectural view on the elimination of useless parts in species], but does not want to publish it as his [CD’s] own. Asks GHD to think carefully before he publishes it.

Sends, with CD’s approval, a clarification of CD’s explanation of how useless organs might diminish [see 9061]. Using Quetelet’s law of normal distribution GHD shows how horns of cattle, having become useless, would gradually diminish and finally disappear.

Has decided to send the letter ["Variation of organs", Nature 8 (1873): 505].

Writes of his poor health and problems of settling in at Trinity.

Asks GHD whether he can tell him what inclination a polished or waxy leaf ought to hold to the horizon in order to let vertical rain rebound off as much as possible.

Sends table showing relative force of impact of weight dropped on a plane inclined at different angles.

On bodies of varying elasticity bouncing off inclined planes [see 9096].

CD gives his criticisms of GHD’s essay on religion and the moral sense. Urges him to delay publishing for some months and then to consider whether it is new and important enough to counterbalance the effects of its publication. J. S. Mill would never have influenced the age as he has done had he not refrained from expressing his religious convictions. Cites John Morley’s Life of Voltaire [1872]: direct attacks produce little effect; real good comes from slow and silent side attacks. "My advice is to pause, pause, pause."

"It is a fearfully difficult moral problem about speaking out on religion, & I have never been able to make up my mind."

An Irishman, a "grand breeder" of short-horns, declared at lunch that CD’s books had been "a great help to [him] in breeding!"

CD writes about organising a subscription for Dohrn’s Zoological Station at Naples. Has drawn up a draft circular for naturalists to sign to show their support for the Station.

Sorry to hear of GHD’s poor health – he could have pleasant society at Cambridge if he were stronger.

Contributes £75 [to a fund for Naples Zoological Station] "if the affair goes on after we hear from Dohrn".

CD is looking for editorial assistance in preparing a new edition of Descent, and inquires whether GHD might be interested in taking on such a tedious job.

Pleased that GHD will help with second edition of Descent. Cautions him not to alter strength of CD’s expression or improve the style too much.

Gives his and CD’s thanks for information on consanguinity among parents of asylum inmates.

Returns and sends comments on Clarke Hawkshaw’s essay ‘The persistence of forms of life in the depths of the sea’.