Sends notes on Infusoria for Ehrenberg.

Comments on distribution of species in natural orders that have local distributions. Intermediate forms between species of Lycopodium.

Differences in variability of species within a single genus. Further observations on Lycopodium.

Interested in Humboldt’s river with different floras on opposite banks, and other unexplained cases of very local distributions.

Would like to visit on the weekend of 7–8 December.

Differences in floras of St Helena and Ascension.

Thanks for pleasant stay at Down.

Remarks on boulders found on southern islands.

Describes the alpine character of the Andes flora and relays information on other mountain floras.

Quotes instances of seeds that retained their vitality after being carried by ocean currents.

Sends notes on the comparative floras of New Zealand, Australia, and west coast of South America.

Encloses a copy of part of a letter from George Gardner in Ceylon concerning the European character of the mountain flora.

Thanks for CD’s comments on "sketch".

Lengthy discussion of geographical distribution and island floras.

Has been "delighted with" [Robert Chambers’] Vestiges [of creation (1844)].

Galapagos flora work goes on well.

Sends comparison of the floras of Society and Sandwich Islands.

Previous letter [missing] on Edinburgh position was ill-tempered. Friends assure him that he ought to be thankful for opportunity to try for professorship.

Reports meeting with Humboldt in Paris.

JDH recommends Augustin de Saint-Hilaire’s Leçons de botanique [1841]. Relates opinions of European botanists on migration and plant distribution.

A Tasmanian Cyttaria is same species as CD’s Fuegian fungus. Did the species originate on the beeches of Fuegia or of Tasmania?

JDH gives interpretation of Vestiges.

John McCulloch, J. F. Schouw, and Lamarck on the species question.

First part of "Galapagos flora" ["Plants of the Galapagos Archipelago", Trans. Linn. Soc. Lond. 20 (1851): 163–233] finished but not printed.

Details of distribution of Galapagos flora. Peculiarity of island floras.

Leaves for Edinburgh on Wednesday.

Answers CD’s questions relating to the flora of the Galapagos. [See 889.]

The translation of Humboldt’s Kosmos [Cosmos (1846–58)] is delayed.

Gives instances of peculiar genera with several good species in very small islands. Scarcity of insects on islands.

JDH cannot prove that there is much hybridising, but does not see why there should not be. "Bother variation, development & all such subjects, it is reasoning in a circle I believe after all."

Raises some points for revision of CD’s Journal of researches.

Southern island floras. "The more I ponder upon Insular Floras the less inclined I am to admit the mutation of species to any very great amount."

JDH’s grandfather’s death.

Collecting testimonials for the Edinburgh chair.

The most experienced botanists argue for the "validity of species in nature". Against taxonomic "splitters".

CD’s Cape Tres Montes plants.

Thanks for Journal of researches.

Puzzled over pea flower from Cape Tres Montes.

Thinks species a fair and most profitable subject for discussion, but has no formed opinion of his own.

Answers CD’s queries arising from Flora Antarctica.

Would like CD to come to town and go over Galapagos plants with him.

Goes on the assumption that each species has one origin, is immutable, and migrates.

Disagrees with Gaudichaud[-Beaupré] that volcanic island species are polymorphous.

Some mundane genera vary, others do not (Senecio vs Gnaphalium).

John Lindley’s doctrine of longevity of trees is amazing.

Edward Forbes’s health is better.

Thanks for Edward Forbes’s letter. Botanical evidence conflicts with parts of his theory but supports others. Is becoming more of a migrationist.

Bentham agrees with JDH on polymorphism.

JDH recognises the existence of "altered states" of continental species in island floras. The botanists’ difficulty in determining a new species is no grounds for dismissing the important question of altered forms.

Will look for Ascension plants for Ehrenberg.

French Galapagos collections confirm JDH’s view that plants arrived from north.

Cannot agree with Forbes on North Atlantic flora.

Botanical definition of "highness" and "lowness" usually means complexity and simplicity.

Some plants, such as aquatic ones, are cleistogamous. Cannot see why they should not be.