Questions on variation in nature: taxa varying in one region but not another. Variation between vs within species. Rarity of variation in important organs within a species. G. R. Waterhouse’s views on variation in highly developed organs, which CD relates to variation in rudimentary organs.

Asks for cases of obligate self-fertilising plants.

[CD annotation proposes using the Steudel Nomenclator botanicus (1821–4) to determine if variable species occur in genera with many species.]

Representative species may complicate tabulation of varieties.

Questions for Mr Anderson about horse colouring in Norway.

Has been writing an "audacious little discussion" to show that "organic beings are not perfect, only perfect enough to struggle with their competitors".

Hermaphrodite trees are enough to "knock" CD down. Can JDH observe Eucalyptus to see whether pollen and stigma mature at same time?

JDH’s facts showing European plants are more common in southern Australia than in South America are disturbing because they are improbable on CD’s views of migration.

JDH said he would give examples of Australian forms that have migrated north along the mountains of the Malay Archipelago.

Replies at length to JDH’s worried reaction to his comments on lowness of Australian plants. CD distinguishes between "competitive highness", i.e., which fauna would be exterminated and which survive if two faunas were placed in competition, and ordinary "highness" of classification.

CL’s comments on Origin. Mentions corrections to last chapter suggested by CL.

Comments on lack of peculiar bird species on Madeira and Bermuda. Emphasises importance of American types in Galapagos.

Denies necessity of continued creation of primitive "Monads".

Denies need for new powers and any principle of improvement.

Discusses gradations of intellectual powers.

Adaptive inferiority and extinction of groups of species and genera.

Asserts that climate is less important than the struggle with other organisms.

Suggests an experiment involving primroses and cowslips.

The chapter on hybridisation.

Rudimentary organs.

Gives opinion of Lamarck’s work.

Inquires about the nature of some money recently paid to him.

Comments on MS by C. S. Bate. Bate not aware of other work on Cirripedia; cites Bate’s errors. Would Bate allow CD to use his drawings in Living Cirripedia? [See Living Cirripedia 1: 9–16.]

Announces birth of his fourth son, Leonard.

Hooker’s imprisonment.

Birth of Leonard Darwin.

Barnacles will never end; on to fossils.

Is sending JSB sponges.

He returns the Plumularia on which the beautiful Scalpellum ornatum was attached. [See 1229.]

Comments on paper by CHLW.

Considers effect of heat on bending of strata, and producing volcanoes and elevation.

"I can have no doubt that speculative men, with a curb on, make far the best observers."

On Himalayan stratigraphy. Believes JDH’s observations of glacial action are the first ever done east of Urals.

Barnacles and the species theory; impressed with variation.

Effect of CD’s species sketch on JDH’s view of willow systematics.

Thanks CSB for drawings of [cirripede] larva and for permission to cite unpublished paper ["On the development of the cirripedes", Ann. & Mag. Nat. Hist. 2d ser. 8 (1851): 324–32]. Describes method of preserving specimens. Mentions Balanus common on tidal rocks at Tenby.

Thanks CSB for cirripede larvae.

Has been unwell.

Cannot see transverse articulation referred to and does not believe in it.

Sends species synonyms.

Discussion of Chthamalinae.

Suggests using asphalt to seal specimen containers.

Comments on mouth of larva.

Discusses share dealings and investment matters.

Discusses the [CD/Emma] marriage trust.

Writes concerning marriage trust.

Thanks MM for reference to Shakespeare’s eleventh sonnet.

Concerning specimens he wants collected in the Azores.

Reports the state of Anne Darwin’s health.