To W. W. Baxter 2 [December 1872]1
Down, | Beckenham, Kent.
You supplied me some little time ago with extract of Belladonna, & many years ago I procured in Bournemouth from a good shop some extract of Digitalis. Both these extracts act on my experimental plants, as if they contained gelatine, or albumen, or some animal matter.—2 In preparing these extracts is any sort of animal matter ever used?
I shd. be very much obliged for an answer & remain | Dear Sir | Yours faithfully | Ch. Darwin
Extract of Hyosciamus & of Colchicum does not act in this manner.—3
Asks about possible animal substances in samples of Belladonna and Digitalis.