Thanks CD for his letter of 1 Jan 1875. Will send a paper on the genus Volvox ["Die Entwicklungsgeschichte der Gattung Volvox", Cohn Beitr. Biol. Pflanz. 1 (1875) Heft 3: 99–115].

Informs CD of his discoveries of the "house"-building capacity of Difflugia, one of the lowest forms of organism.

Sends CD his writing on Aldrovanda and Utricularia, which he is welcome to use in his forthcoming book [Insectivorous plants].

Has observed a Dionaea fertilised without insect aid.