Has made observations on pollination mechanism in Medicago sativa [J. Linn. Soc. Lond. (Bot.) 9 (1867): 327–9], which his brother-in-law [J. D. Hooker] would accept. Wants to check that CD has not already made them.
Also sends interpretation of Salvia.
His observations come from following CD’s generalisation in Origin [p. 79] on necessity of out-crossing.