Confirms CGBD’s impression given in a letter to J. S. Henslow that CD in the Origin did not touch directly upon the final causes of sexuality, which CD considers one of the "profoundest mysteries in nature". CD is inclined to stress sexuality as the means of keeping forms constant and checking variation although he grants its role in the origination of varieties. [See 2869.]

His thanks for the pamphlet ["Remarks on the final causes of the sexuality of plants" (1860)] and the extremely kind and liberal manner in which Daubeny alludes to CD’s work.

Further discussion of sexual generation and CD’s suspicion that its most important function remains hidden.