⁠⟨⁠My dear D^r. Sanderson⁠⟩⁠

I ⁠⟨⁠$\frac{4}{5}$ line⁠⟩⁠ or will ⁠⟨⁠$\frac{3}{4}$ line⁠⟩⁠ Germany. ⁠⟨⁠$\frac{2}{3}$ line⁠⟩⁠ having a ⁠⟨⁠$\frac{3}{5}$ line⁠⟩⁠ Southampton, & return home next Monday.— I shall soon work in some new facts in my Chapt. on digestion by Drosera,² & I want to ask one question ⁠⟨⁠1 word⁠⟩⁠ you can let me ⁠⟨⁠$\frac{2}{5}$ line⁠⟩⁠ ⁠⟨⁠4 or 5 lines⁠⟩⁠ suggested ⁠⟨⁠$\frac{3}{4}$ line⁠⟩⁠ne & was ⁠⟨⁠$\frac{3}{5}$ line⁠⟩⁠ted. But when not thus treated, it was never completely digested, & the residue does not consist solely of starch. Now in your experiments with artificial digestive fluid, ⁠⟨⁠$\frac{1}{3}$ line⁠⟩⁠ ⁠⟨⁠interlineation at top of page⁠⟩⁠ any of the fatty acids did you find the gluten which has not been soaked in hydrochloric acid was digested slowly or imperfectly?³ One other result has surprised me, viz the fibro-cartilage is not digested: my son Frank, made with pepsin & H. acid some artificial digestive fluid, which at the temperature of the room well digested fibrin, but would not digest fibro-cartilage, though it rendered it hyaline & swollen, just as did Drosera.—⁴

You must read Hooker’s address to Bot. Section at Belfast, & see what a magnificent digester is Nepenthes.—⁵ I have been almost driven mad by Utricularia which catches no end of entomostraca, but cannot digest, & I believe, though I cannot prove it, that it absorbs the products of putrefaction.⁶

Yours most sincerely | Ch. Darwin