To Mary Treat 1 June 1876
Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R. [Hopedene, Surrey.]
June 1st 76
My dear Madam
I have received your kind letter & the article which I have read with the greatest interest. It certainly appears from your excellent observations that the valve was sensitive, & I hope it may be so from homologising with Pinguicula; but I cannot understand why I could never with all my pains excite any movement. It is pretty clear I am quite wrong about the head acting like a wedge.—1 The indraught of the living larvæ is astonishing.— I do not at all understand the German account of the development of the utricles & I suspect that these Germans did not look to young enough utricles.2
I am not well & am staying away from my home for rest, so pray excuse brevity.3 Wishing you success of every kind in your admirable work
I remain | Dear Madam | Yours very faithfully | Ch. Darwin
Thanks MT for her article ["Is the valve of Utricularia sensitive?", Harper’s New Mon. Mag. 52 (1875): 382–7]. Does not understand why he failed to detect movement [in Utricularia], but it appears from her observations that the valve is sensitive.