Reports long preparation of work on how species and varieties differ. Agreement with Wallace’s conclusions as reported in Annals and Magazine of Natural History and in his letter to CD of 10 0ct [1856]. On distinction between domestic varieties and those in "a state of nature".

On mating of jaguars and leopards, the breeding of poultry, pigeons, etc.

Requests help for his experimenting on means of distribution of organic beings on oceanic islands.

Comments on agreement of their respective views on distribution.

Reference to differences on subsidence.

Reports on progress of his work and praises ARW’s investigations.

Expresses pleasure and relief at ARW’s response to joint publication of their pieces about natural selection.

Plans for the "abstract" [Origin].

Birds’ nests as evidence of variation of instincts.

Their collection of bees’ combs.

Praises ARW’s article.

Lyell’s and Hooker’s views [of species issue].

First part of Origin MS is with Murray;

CD hopes he has noticed ARW’s work fairly.

ARW is right in thinking that CD was led to believe that selection was the principle of change from studying domesticated productions and that after reading Malthus he "saw at once how to apply this principle". Geographical distribution and geological relations of extinct and recent inhabitants of S. America first led him to the subject, "Especially case of Galapagos Islds". Hooker and Lubbock are full converts and Huxley now believes in species mutation. "We shall live to see all the younger men converts."

Praises ARW’s work and spirit.

CD had actually written a letter to ARW stating he would not publish before him but was persuaded by Lyell and Hooker to allow them to act "as they thought fair & honourably".

Will forward ARW’s "admirable" paper to Linnean Society ["On the zoological geography of the Malay Archipelago", J. Linn. Soc. Lond. (Zool.) 4 (1860): 172–84].

Discusses geographical distribution of animals in the Malay Archipelago; relation of distribution to depth of sea between islands.

Relation of Celebes to Africa almost passes belief.

Differs wholly from ARW on colonisation of oceanic islands; does not believe in Forbes’s great continental extensions.

Anticipates Owen’s opposition to their views, but "he is a poor reasoner & deeply considers the good opinion of the world, especially the aristocratic world".

A copy of CD’s book [Origin] has been sent to ARW; invites his comments. "God knows what the public will think". Hooker believes Lyell is a convert, but CD does not think so, although he is "deeply interested". If he can convert Huxley, CD will be content.

Pleasure in ARW’s approbation of the Origin. Other supporters among scientists. ARW’s generosity.

Attacks by Owen, Sedgwick, and others.

Anticipation of natural selection by Matthew in 1830.

Quarterly Review piece written by Bishop Wilberforce with aid of Owen.

Other reviews mentioned.

Health.

Family illnesses.

On disposition of wild honeycomb gift.

Discounts the difficulty presented by ostrich wings.

Baffling problems with Melastoma. Appreciates ARW’s help with it and the "gorze case".

Has read report of ARW’s paper [to Newcastle BAAS meeting, "On the geographical distribution of animal life"] in the Reader [2 (1863): 352–3].

Asa Gray’s high opinion of ARW as a reviewer [reference to S. Haughton’s paper on bees’ cells, Ann. & Mag. Nat. Hist. 3d ser. 11 (1863): 415–29, reviewed by ARW in "Remarks on the Rev. S. Haughton’s paper", Ann. & Mag. Nat. Hist. 3d ser. 12 (1863): 303–9].

Has seen that ARW has read a paper to the Linnean Society.

Thinks that Herbert Spencer’s Social Statics (Spencer 1851) would be too deep for him.

Response to ARW’s papers on Papilionidae ["On the phenomena of variation and geographical distribution", Trans. Linn. Soc. Lond. 25 (1866): 1–71; abstract in Reader 3 (1864): 491–3],

and man ["The origin of human races", J. Anthropol. Soc. Lond. 2 (1864): clviii–clxxxvi].

The former is "really admirable" and will be influential.

The idea of the man paper is striking and new. Minor points of difference. Conjectures regarding racial differences; the possible correlation between complexion and constitution. His Query to Army surgeons to determine this point. Offers ARW his notes on man, which CD doubts he will be able to use.

On sexual selection in "our aristocracy"; primogeniture is a scheme for destroying natural selection.

[Letter incorrectly dated March by CD.]

Short reply to ARW’s long letter. Reaffirms belief in sexual selection.

Postscript on M.-J.-P. Flourens’ "little dull book against me" [Examen du livre de M. Darwin (1864)].

Commends ARW’s papers on parrots

and on the theory of geographical distribution [see 4750].

Wild pigs in Aru Islands must have been introduced and later ran wild. Does ARW have an opinion on the subject?

Exchange of photographs.

Aru pigs present perplexing case, whether wild or domesticated.

Crests as inherited variations; domesticated birds.

Belief in value of travel journals.

Current reading.

Welcomes ARW’s paper on pigeons ["On the pigeons of the Malay Archipelago", Ibis 1 (1865): 365–400].

Influence of monkeys on distribution of pigeons and parrots.

Asks ARW to explain a passage in his paper on Malayan Papilionidae [Trans. Linn. Soc. Lond. 25 (1866): 1–71] on how dimorphic forms are produced. CD knows of varieties "that will not blend or intermix", but which produce offspring quite like either parent.

ARW’s remarks on geographical distribution in Celebes "will give a cold shudder to the immutable naturalists".

Presses ARW to work on his travel journal.

ARW’s simple explanation of dimorphic forms is satisfactory.

On "non-blending" of certain varieties, CD thinks ARW has not understood him. He does not refer to fertility. He crossed two differently coloured varieties of peas and "got both varieties perfect, but none intermediate". Something like this must occur in ARW’s butterflies.

CD considers "the survival of the fittest" as alternative term to "Natural Selection". Reflections upon misunderstanding and his own ambiguity.

Health improved; can now work "some hours daily".