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".

Will call on Wallace tomorrow (Saturday) at 10.