Regrets he cannot hear lecture by F. C. Donders.

Hopes to see WB before he returns home.

Comments on FD’s discovery – "if it so proves". It will be important to see whether the protoplasm oozes through the cell-walls [of Dipsacus] or whether it can be withdrawn.

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.