CD now has a sufficiently large collection of [skeletons of] chickens to be able to tell how far the young differ proportionally from the old.

He goes on accumulating facts; what he will do with them "remains to be seen".

Attended Glasgow BAAS meeting. "Duke of Argyll spoke excellently" [Rep. BAAS (1855): lxiii–lxxxvi].

Lists his pigeon collection.

Thanks WDF for his help and reports on progress in "the Cock and Hen line of business". Has written to every quarter of the world for skins of poultry and pigeons.

As for seeds, Hooker and Bentham obstinately refuse to believe they can live even a few years in the ground.

Believes WDF’s case of mongrel Scotch deerhound is very valuable for him.

Mentions his work on pigeons and chickens.

Fears sometimes he will break down: "My subject gets bigger and bigger".

Thanks WDF for specimen of Dorking cock.

Sketches the Beagle’s travels – Rio de Janeiro, Montevideo, cruise to the south and return – and what the future holds. Writes with nostalgia of England and says he sees no end to the voyage.

He enjoys and has been lucky principally in geology and among pelagic animals; has found remains of large extinct animals.

The responses to his queries on domestic variations are coming in from all over; believes he will make an interesting collection. At present concerned with rabbits and ducks.

Has told Lyell of his views on species and CL urges CD to publish a preliminary essay. Has begun to work on it, with fear and trembling at its inadequacies.

Does not intend to work systematically on cats. Their origin is in doubt and they have been crossed too many ways.

It would be valuable to know whether half-bred ducks are fertile inter se or with a third breed. Is investigating this with pigeons.

Finds his grief over his daughter Anne’s death still strong.

Is following Lyell’s advice about publishing his species doctrine. It is not to be a sketch, however, but as perfect as his 19 years of work will allow. His work on pigeons has been invaluable on many points. "No subject gives me so much trouble as means of dispersal of terrestrial production in the oceanic islands."

Finds "most remarkable differences" in skeletons of rabbits.

Has taken birds with seeds in crops to Zoological Society and fed them to eagles and owls. Pellets with seeds in perfect condition were "thrown up" in 18 and 16 hours, showing an effective means of distribution.

Asks WDF to write to his nephew in Jamaica to try experiments with floating lizards’ and snakes’ eggs in sea-water, to see if they survive.

Birth of his sixth son [C. W. Darwin]. It is dreadful "to think of all the sendings to school and the professions afterwards".

CD is not well but has not the courage for water-cure again; trying mineral acids.

Working hard on the book [Natural selection]; is overwhelmed with riches in facts and interested in way facts fall into groups.

To his surprise [Helix pomatia] has withstood 14 days in salt water.

Pigeons’ skins come in from all parts of the world.

Helix pomatia is quite healthy after 20 days’ submersion in salt water.

On peas, the evidence is on WDF’s side, but CD cannot see how they can avoid being crossed.

He is working hard, wishes he "could set less value on the bauble fame"; would work as hard, but with less gusto, if he knew his book would be published forever anonymously.

He misses society. "I often conjecture what will become of me; my wishes certainly would make me a country clergyman. – You expect sadly more than I shall ever do in Nat. Hist: I am only a sort of Jackall, a lions provider; but I wish I was sure there were lions enough."

Has collected a host of minute beetles, some reptiles, small quadrupeds, and fishes. Invertebrate marine animals are his delight. The pleasure of working with microscope ranks second only to geology.

His impressions of the hydropathic establishment and E. W. Lane. Is convinced the only thing for "chronic cases" is the water-cure.

Asks if WDF knows of any breed of pig that originated or was modified by a cross with a Chinese or Neapolitan pig, and whether the crossbreed bred true.

Has come to think his brains were not made for thinking – he immediately feels better when at Moor Park.

News of his family.

Thanks WDF for his letter about a rabbit breed that he thinks is the Himalaya. He is particularly glad to hear of it because it breeds so true.

Asks to borrow W. C. Hewitson’s book [British oology, 2 vols. (1831–44)].

CD is searching for reliable information on slight variations in the degree of perfection of nests of the same species of birds.

Thanks WDF for information on blackbirds’ nests [see Natural selection, p. 505].

Problem of choosing from among the load of curious facts for chapter on "Instinct" [Natural selection, ch. 10; Origin, ch. 7] perplexes him.

Asks about behaviour of chicks in danger and whether crossed animals are wilder than either parent.

Thanks for Hewitson [British oology].

Has found more variability in birds’ nests than he expected.

Interested in WDF’s note about turkey terrified by a frog [see Natural selection, p. 488 n.].

WDF’s nephew has forgotten to mention the most important element, whether the lizards’ eggs floated and stayed alive on sea-water.

Thanks for facts about turkeys and terrier [see Natural selection, p. 481 n.].

Writes of his ride from Rio Negro to Bahia Blanca and Buenos Aires, which he undertook in order to learn the geology of the land, so full of bones of large extinct quadrupeds.