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.

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.