JDH not happy with CD’s explanation of the absence of north temperate forms in the Southern Hemisphere, given his explanation for the spread of sub-arctic forms to the south. [CD’s note is in response to JDH’s criticism.]

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.

No summary available.