Summary

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.]

Summary

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

Summary

JDH approves MS section on geographical distribution.

Never felt so shaky about species before.

His objections to some mechanisms of distribution that CD proposes.

Summary

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.

Summary

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.

Summary

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

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

Summary

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.

Summary

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.

Summary

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

Summary

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

Summary

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.

Summary

On the variety of species definitions prevalent among naturalists.

Summary

Has been looking at separation of sexes in poplars.

Interested in reversion.

Does not understand all CD said on inheritance.

JDH now remembers that Origin was "published" some time before it was "distributed" and therefore appeared prior to his own essay [see also 2478].

Impossible to say whether some Dipterocarpaceae survived a cold period or have developed since.

Summary

CD finds Alphonse de Candolle very useful, though JDH has low opinion.

CD argues for accidental introductions explaining some odd distributions, e.g., New Zealand vs Australian plants.

CD’s method.

Diverging affinities in isolated genera.

Summary

CD will advise W. F. Daniell on collecting.

Summary

CD will advise Daniell not to apply for Royal Society grant.

CD’s experiment: fish fed seeds, which germinated when voided.

Summary

Separation of sexes in trees [U. S.].

Do plants offer positive evidence for "continuous land" theory?

Protean genera.

Summary

Ranges of species in large vs small genera: Asa Gray’s compilation fits CD’s expectation.

CD studies seedling mortality in his weed garden.

JDH’s work on Indian flora.

Summary

Independence of variation from climate shown by several plant genera; CD asks for confirmation.

Progressing with book [Natural selection].

Summary

JDH cites W. H. Harvey’s observations on Fucus and David Don’s on Juncus as examples of variations that are independent of climate. There are many such cases. Gives his working scheme for categorising variation.