Mr. Darwin has done me the honour of calling my attention to one or two points in my paper, published in your last number, “On the Fertilisation of Winter-flowering Plants.”¹ He thinks there must be some error in my including Vinca major among the plants of which the pollen is discharged in the bud, as he “knows from experiment that some species of Vinca absolutely require insect aid for fertilisation.”² On referring to my notes, I find them perfectly clear with respect to the time at which the pollen is discharged. My observation, however, so far agrees with Mr. Darwin’s, that I find no record of any fruit being produced in January; it was, in fact, the absence of capsules on the Vinca which induced me to qualify the sentence on this subject, and to say “in nearly all these cases, abundance of fully formed seed-bearing capsules were observed.”³ It is worthy of remark, that the Vinca is the only species in my list of apparently bud-fertilised plants not indigenous to this country.⁴ The second point relates to the white dead-nettle, with respect to which Mr. Darwin says, “I covered up Lamium album early in June, and the plants produced no seed, although surrounding plants produced plenty.”⁵ This again would agree with my conjecture that it is only the flowers produced in winter that are self-fertilised. I may, however, be permitted to suggest that the test of covering up a plant with a bell-glass is not conclusive on the point of cross-fertilisation, as it is quite probable that with plants that are ordinarily self-fertilised, the mere fact of a complete stoppage of a free circulation of air may prevent the impregnation taking place. Has the experiment ever been tried with grasses, which, according to the French observer, M. Bidard are necessarily self-fertilised?⁶

3, Park Village East, Nov. 8, 1869