The year is established by the relationship between this letter and the letter to E. Schweizerbart’sche Buchhandlung, [19 March 1867].

The letter to which this is a reply has not been found, but evidently concerned the German translation of Variation. CD had offered to send clean proof-sheets of Variation to the German publisher Christian Friedrich Schweizerbart on condition that the translation was made by Julius Victor Carus, and had advised Schweizerbart to negotiate with Murray about stereotypes of the illustrations (see letter to E. Schweizerbart’sche Buchhandlung, [19 March 1867]). Schweizerbart wrote to CD on 22 March 1867 accepting his terms and saying that he had written to Carus to ask whether he would accept the commission.