Summary

On the Borneo cave exploration.

ARW will send his contribution to theory of origin of man. The vast mental and cranial differences between man and apes, whereas structural differences in other parts of body are small. The problem of explaining diversity of human races along with the stability of man’s form during all historical epochs. Discussion with "Anthropologicals" [following reading of ARW’s paper, "The origin of human races", before the Anthropological Society, 1 Mar 1864].

Summary

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.]

Summary

Argues the antiquity of the human species because natural selection acts differently with respect to men. Changes in man are largely confined to head and brain. Warfare and sex are very uncertain as means of selection.

Gives CD complete credit for theory of natural selection.

Is beginning his narrative of his travels.

Lyell argues against tracing man as far back as Miocene times. R. I. Murchison’s argument that Africa is the oldest existing land implies that Africa is the place to look for early man.

Summary

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)].

Summary

His distress that his engagement has been broken off.

Sends copies of two papers ["On the parrots of the Malayan region", Proc. Zool. Soc. Lond. (1864): 279–97;

"On the physical geography of the Malay Archipelago", J. R. Geogr. Soc. 33 (1863): 217–34].

Summary

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?

Summary

Sends papers with comments. Convinced that the Aru pig is a species peculiar to New Guinea fauna, not a domestic animal that ran wild.

Admires CD’s paper ["Three forms of Lythrum", Collected papers 2: 106–31].

Summary

Exchange of photographs.

Aru pigs present perplexing case, whether wild or domesticated.

Summary

Thanks CD for paper ["Climbing plants"].

Reports case of variation becoming at once hereditary – a crested blackbird with crested young.

Summary

Crests as inherited variations; domesticated birds.

Belief in value of travel journals.

Current reading.

Summary

Information concerning improvements in the Reader under new sponsorship.

Current reading and work [on pigeons for Ibis 1 (1865): 365–400, and catalogue of his collection of birds].

Book of travels postponed indefinitely.

Summary

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.

Summary

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.

Summary

Looks forward to reading Variation.

Explains how two or more female forms occur in one species through selection. The physiological problem remains of how each produces offspring like the other without intermediates. Is not CD’s case of varieties that will not blend the physiological test of a species needed for "complete proof of the origin of species"?

"Travels" postponed.

Summary

Lengthy analysis of sources of misunderstanding of natural selection. Advocacy of Spencer’s term "survival of the fittest" instead of "Natural Selection". ARW urges CD to stress frequency of variations.

Summary

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".

Summary

Thanks CD for 4th ed. of Origin.

Discusses abnormal sexual characters produced by mimicry. ARW’s papers on the subject.

Agassiz’s "marvellous" Amazonian glacier theory.

Summary

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.

Summary

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.

Summary

Protective role of colours in caterpillars and butterflies. Sexual differences in colours of butterflies.