Now for my question. Exactly in the middle of the filament of the normal anther, and exactly in the middle of the lateral membrane of the clinandrum, and running up to the same height, are quite similar bundles of spiral vessels; ending upwards almost suddenly. Now is not this structure a good argument that I interpret the homologies of the sides of clinandrum rightly? (602/2. Though Robert Brown made use of the spiral vessels of orchids, yet according to Eichler, "Bluthendiagramme," 1875, Volume I., page 184, Darwin was the first to make substantial additions to the conclusions deducible from the course of the vessels in relation to the problem of the morphology of these plants. Eichler gives Darwin's diagram side by side with that of Van Tieghem without attempting to decide between the differences in detail by which they are characterised.) I find that the great Bauer does not draw very correctly! (602/3. F. Bauer, whom Pritzel calls "der grosste Pflanzenmaler." The reference is to his "Illustrations of Orchidaceous Plants, with Notes and Prefatory Remarks by John Lindley," London, 1830-38, Folio. See "Fertilisation of Orchids," Edition II., page 82.) And, good Heavens, what a jumble he makes on functions. LETTER 603. TO J.D. HOOKER. Down, October 22nd. [1861]. Acropera is a beast,--stigma does not open, everything seems contrived that it shall NOT be anyhow fertilised. There is something very odd about it, which could only be made out by incessant watching on several individual plants. I never saw the very curious flower of Canna; I should say the pollen was deposited where it is to prevent inevitable self-fertilisation. You have no time to try the smallest experiment, else it would be worth while to put pollen on some stigmas (supposing that it does not seed freely with you). Anyhow, insects would probably carry pollen from flower to flower, for Kurr states the tube formed by pistil, stamen and "nectarblatt" secretes (I presume internally) much nectar. Thanks for sending me the curious flower. Now I want much some wisdom; though I must write at considerable length, your answer may be very brief. (FIGURE 8.--FLORAL DIAGRAM OF AN ORCHID. The "missing bundle" could not be found in some species.)