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894 DARWIN (CHARLES, 1809-1882). Naturalist and Author.

AUTOGRAPH LETTER SIGNED TO J. JENNER WEIR.

7 pp., 8vo. Beckenham, 17th March (1870). With addressed envelope. £10 10s

An exceedingly interesting letter concerning reproduction in animals, etc., and referring to his own book on domestic animals.

895 DARWIN (CHARLES).

LETTER SIGNED WITH AUTOGRAPH CORRECTIONS TO SIR LAUDER BRUNTON.

4 pp., 8vo. Down, Beckenham, 3rd December, 1873. £5 5s

An extremely interesting letter relating to the nourishing powers of Chondrin and Gelatin, the digestibility of Chlorophyl, etc.

"…With respect to Chondrin, Dr 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 Chondrin seems to excite the plant more than does Gelatin, tho' neither do so to at all an equal degree as does albumen. Dr 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 Chondrin was prepared for me by Dr C. Moore of Brixton Road 3, but whether it was absolutely pure, I cannot of course say.

"If anything is known of the relative powers of nourishment of Chondrin and Gelatin, I should 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." Etc.