Tristan da Cunha flora.

Aquatic plants.

Density and diversity of plants in small plots in Kent, Keeling Islands, and Himalayas.

Whether or not there should be movement of particles according to Tyndall’s theory of glacial action ["Observations on glaciers", Not. Proc. R. Inst. G. B. 2: 54–8, 441–3].

CD subscribes to H. C. Sorby’s view of gneiss [Edinburgh New Philos. J. 55 (1853): 137–50].

Seed-salting.

Pigeons.

Significant differences in skeletons of domesticated rabbits.

Will send MS on one point of geographical distribution. It is "of infinite importance" that JDH see it, for CD has never felt such difficulty in deciding what to do.

Wants capsules of aquatic plants, to float in sea-water.

Note accompanying MS of part of chapter 11 ["Geographical distribution"] of Natural selection [1975].

Podostemaceae flowering under water.

Agrees with JDH that Cytisus report [presumably of a large change] not sound. CD pleased because, if true, species would change too quickly.

CD coming to London.

Read JDH’s review [Hooker’s Kew J. Bot. 8 (1856): 54–64 et seq.] of Alphonse de Candolle’s Géographie botanique raisonnée [1855] long ago.

Sends JDH part of MS for chapter 3 of Natural selection ["Possibility of all organic beings crossing"] to be corrected and returned.

JDH’s report of Podostemon flowering cleistogamously under water in Bengal.

[Copious revision by JDH.]

CD sorry he had to leave the Hookers abruptly to catch his train.

JDH approves MS section on geographical distribution.

Never felt so shaky about species before.

His objections to some mechanisms of distribution that CD proposes.

CD relieved by JDH’s positive response to his MS.

CD continues observations on means of transport.

JDH’s Raoul Island paper [J. Linn. Soc. Lond. (Bot.) 22 (1857): 133–41], showing continuity of vegetation with New Zealand, best evidence yet of continental extension.

CD finds JDH’s objections to a mundane cold period significant, and he endeavours to show how they do not rule out mutability.

He is writing on crossing.

CD encloses letter from Asa Gray, although it is critical of JDH.

Role of struggle in forming species in retreat from advancing glaciers.

Continued debate on formation of species as a result of retreat from glaciers.

JDH suggests internal powers of species modification, which he knows CD abhors.

CD, attempting to clarify debate, states more of his position. External conditions cause "mere variability". Formation of species due to selection. Relation of an organism to its associates far more important than external conditions.

Questions JDH on separation of sexes in trees in New Zealand flora.

Has done New Zealand flora calculations. Results support CD’s theory of necessity of crossing. Trees tend to have separate sexes.

CD is convinced of relation between separation of sexes and tree-habit.

Recent hard blows against crossing theory.

CD long tormented by land molluscs on oceanic islands; found transport possible experimentally.

On the variety of species definitions prevalent among naturalists.

No summary available.