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".

CD now acknowledges that the sometimes very great sexual, i.e., ornamental, differences in fishes offer a difficulty to the view that females are not brightly coloured on account of the danger to propagation of the species.

Asks why caterpillars are sometimes beautifully coloured. It poses a problem for view that sexual selection is the explanation of colours of male butterflies.

More on mimetic butterflies.

ARW’s explanation of protective value of conspicuous coloration is ingenious.

CD still holds to sexual selection with respect to beauty in male butterflies.

Sexual selection and the races of man.

Expression of emotions is another subject he plans to include in his essay [Descent].

Asks ARW to suggest an observer in Malay Archipelago to whom he might send queries [on expression].

Asks to be kept informed on gaudy caterpillars.

Problems of his work on man; scope and role of sexual selection.

Indulgence of interest in expression is simply a "hobby-horse". Will see whether he can get queries inserted in an Indian newspaper.

Comments on ARW’s view of colouring in relation to sexual selection and protection. It is not new to CD. Hopes to discuss subject fully in his "Essay on Man" [Descent]. As to the problem of brightly coloured females, CD is not satisfied that it is due to males taking over incubation. Admires "value and beauty" of ARW’s generalisations.

Returns ARW’s notes. He will work up subject much better than CD.

Apologises for the note of illiberality in his letter regarding ARW’s work on the colouring and other sexual differences in mammals.

Discusses laws of inheritance based on sexual selection.

He questions the extent of applicability of principles of protection and sexual selection to lower animal forms, though Ernst Haeckel has shown how protection may account for transparency and absence of colour in lower oceanic animals.

Acknowledgment of article on mimicry [Westminster Rev. 88 (1867): 1–43].

Response to ARW’s "Creation by law", especially the Angraecum sesquipedale and the predicted Madagascar moth.

ARW’s argument on beauty strikes CD as good.

Wishes ARW had made more clear the assumption of the reviewer [in North Br. Rev.] that each variation is a strongly marked one.

The Duke of Argyll’s argument on beauty is not candid.

Reports work on sexual selection. Problems with the relative numbers of the two sexes and polygamy. Asks ARW’s help with several questions on polygamous birds.

Pleased by ARW’s response to Pangenesis.

On negative reception by his friends.

Further argument concerning sterility and natural selection.

Polygamy and sexual selection.

Protection.

Grateful for addresses of informants, especially that of Rajah James Brooke.

Dispatch of queries on expression. Answers will make interesting appendix to his "Essay on man" [Descent].

Protective adaptation of female butterflies believed probable.

Believes in sexual selection as applied to man.

On his Primula paper for the Linnean Society ["On the specific difference between Primula veris, Brit. Fl. (var. officialis, Linn.), P. vulgaris, Brit. Fl. var. acaulis, Linn.), and P. elatior, Jacq.; and on the hybrid nature of the common oxlip; with supplementary remarks on naturally produced hybrids of the genus Verbascum", [officinalis!?] J. Linn. Soc. Lond. (Bot.) 10 (1869): 437–54].

Peacocks and sexual selection.

ARW’s sterility argument has driven CD’s sons half-mad.

On problem of sterility, CD cannot persuade himself that it has been gained by natural selection.

On sexual selection and minute variations, he tends to agree with ARW. Sends George Darwin’s notes on ARW’s argument.