An account of his observations on Aldrovanda and Utricularia.

Sends CD his memoir on Aldrovanda [Beitr. Biol. Pflanz. 1 (1875) Heft 3: 71–92] in advance of publication [see Insectivorous plants, pp. 321 et seq., 395–6].

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.

Acknowledges presentation copy of Insectivorous plants.

Studying Drosera on vacation in Bohemia. Thinks CD has erred in considering "aggregation" to have occurred in the protoplasm. Suggests it is result of exosmosis of vacuole.

Clarifies his thoughts on "aggregation" in Drosera.

Has had doctoral student [Alexander Fraustadt] working on the physiology and chemistry (i.e., chlorophyll and starch distribution) and comparative anatomy of Dionaea.

Acknowledges presentation copy of Cross and self-fertilisation.

Thanks for visit to Down.

Praise for CD’s theories.

Praises unbroken series of CD’s and Francis [Darwin]’s botanical works.

Confirms FD’s Dipsacus observations. Problem of interpreting microscopic filaments as protoplasm or as inorganic and osmotic artifacts.

Accepts CD’s offer to publish his letter, confirming Francis Darwin’s observations [see Collected papers 2: 205–7].

H. Hoffmann’s observations on Amanita contractile filaments must be repeated.

Microscopic examination of secretory gland filaments in Dipsacus leafcups. FD’s pseudopod theory of Dipsacus.

Sends details of H. H. R. Koch’s work on bacteria, including first photographs.

J. S. Burdon Sanderson’s and Koch’s collaboration on systemic fever.

Thinks movement of Francis Darwin’s Dipsacus filaments is an artifact.

Response to Movement in plants. Setting out to confirm CD’s experiments. Believes plant cell motion, like that of animals, depends on protoplasm more than water.