Describes his lectures on CD’s theory.

Thanks CD for copy of Variation. Comments on book.

Describes work of two protégés in Jena: Nicolas von Miklucho[-Maclay] and Anton Dohrn.

His cousin, Wilhelm Bleek, is sending an article about the origin of language.

Asks to keep book a few months longer but will return it if CD needs it [Webb and Berthelot, Histoire naturelle des Îles Canaries, vol. 3, pt 1: Géographie botanique (1840)].

Describes research on Siphonophora.

Describes life in Jena. Mentions alpine accident during wedding trip.