Sends his MS on Dionaea and hopes it may be useful for JSBS’s lecture ["On the mechanism of the leaf of Dionaea muscipula", Not. Proc. R. Inst. G. B. 7 (1874): 332–5].

Thanks for MS which he intends to read while on a week’s holiday.

Sends thanks for Francis Darwin’s offer of help and says that Francis’s experiments on digestion are complete.

Sends results of experiments on digestion. Encloses two sets of notes: "Experiments on the digestibility of certain preparations sent by Mr Darwin" and "Note for Mr Darwin" [marked by CD for insertion in ch. 6 of Insectivorous plants].

Thanks for the careful experiments, particularly on organic acids.

Purpose of experiments was to determine digestive activity of liquids containing pepsin. Gives required amounts of hydrochloric, propionic, butyric and valerianic acids. Describes experiment and gives results. Also experimented on digestive activity of butyric acid at greater temperatures than the termperature of the body.

Thanks for the acid digestion experiments, which can be printed as they are. CD trying Drosera on dentine and enamel.

Reports results of experiments comparing digestibility of gluten and fibrin for CD’s work on Drosera.

Discusses digestion by insectivorous plants, asks JSBS to try same experiments using pepsin as the digestive agent to see how the results compare with CD’s observations on digestive power of Drosera.

Sends CD provisional information that artificial gastric juice dissolves bone entirely and that gluten and fibrin are completely dissolved in hydrochloric, propionic, and butyric acids. [See Insectivorous plants, pp. 118–19.]

Thanks JSBS for his work. CD concludes the ferment of Drosera must differ from pepsin.

JSBS’s article in Nature ["Venus’s fly-trap", 10 (1874): 105–7, 127–8] could not have been better done.

Has found another plant, Pinguicula, which can catch and digest flies.

Sends cartilage from cat’s ear, the elastic fibres of which will probably resist digestion [by Drosera]. Is preparing fibro-cartilage, which he expects will be digested easily. [See Insectivorous plants, p. 104.]

Thanks for fibrin. Drosera and Pinguicula dissolve it thoroughly.

Is delighted to hear that Pinguicula and Drosera digest fibrin. Suggests diluting gluten in weak hydrochloric acid to remove starch. Enamel was nearly digested [by Drosera] overnight. Would like to try separating the digestive ferment of Pinguicula.

Reports difficulties in experiments on digestion of fibro-cartilage. Asks about JSBS’s experiments with artificial digestive fluids.

JSBS must read Hooker’s address at Belfast [Rep. BAAS 44 (1874): 103–16] to see what a magnificent digester Nepenthes is.

Will prepare experiments with the fatty acids on digestion of gluten. Has found it is digested slowly, but entirely, with pepsin and hydrochloric acid.

Has been testing the digestive powers of Drosera; wants to know whether a group of substances that elicit similar responses are related.

Suggests an explanation for difference in excitability of Drosera leaves to meat and albumen on the one hand and, on the other, fibrin, areolar tissue, gelatin, and fibrous basis of bone.

Discusses the powers of digestion of Drosera and why certain substances produce less excitement in the plant than others.

Responds to CD’s questions about relation to gelatin of areolar tissue, fibrous basis of bone, and other substances CD is using in his work on digestion of Drosera.