My dear Sir

I am very much obliged for your kind note & offers of assistance.¹ With respect to Chondrin, D^r B. Sanderson has rather mistaken my question; it was whether Chondrin is known to be more nutritious to animals than is Gelatin. Drosera digests the one as well as the other, but Chrondrin seems to excite the plant more than does Gelatin, tho’ neither do so to at all an equal degree as does Albumen—²

D^r Sanderson suggested to me that my Chondrin may not have been quite pure, whereas the gelatin was pure, having been prepared for me by Hoffman. The Chrondrin was prepared for me by D^r C. Moore of Brixton Road; but whether it was absolutely pure, I cannot of course say.³

If any thing is known of the relative powers of nourishment of Chondrin & Gelatin, I sh^d be grateful for the information.

It occurred to me as just possible, after seeing their different action on Drosera, that the many disputes about the value for nourishment to man of Gelatin might be due to different forms having been used.

I much wish to know whether Chlorophyl is digested by animals, as it was so very imperfectly or hardly at all by Drosera. Unfortunately Dr Sanderson has mislaid the bottle: if it is not found within a month or two, I w^d ask D^r Moore to prepare a little more in the same manner as he did before, & then I w^d beg your or Dr S. to test its digestibility. Or perhaps I c^d. get some one else to prepare some.⁴

Your remarks on 2 shades of expression being combined on opposite sides of the same painted face is quite new & surprized me much. I will keep the subject in mind, but I hardly expect to see any such case on a living countenance.⁵

With very sincere thanks | yours very faithfully | Ch. Darwin