i. 9 December 1859 - Marbais - Offers to exchange rare phaneregamous plants collected in Brazil, Guyana and New Holland by Claussen, Libon, Kegel Hartmann, Stephenson and Peiss, etc. for mosses, lichens, algae and Jungermannia.
ii. 29 January 1860 - (Marbais) - Acknowledges mosses and enquires about algae.