. Text-book of botany, morphological and physiological. Botany. FIG. 19.—B a young pollen-grain of Funkia ovata; the knob-like thickenings projecting out- wards are still small; in the older pollen-grain C they are larger; they are arranged in lines united into a FIG. 20.—Ripe pollen-grain of Cichorium Iwtybus; the almost spherical substance of the cell-wall is furnished with ridge-like thickenings united into a net-work; each of these bears thickenings which project still more, in the form of spines arranged like a comb. Fig. 18 bis.—Piece of an annular vessel from the fibro-vascul
. Text-book of botany, morphological and physiological. Botany. FIG. 19.—B a young pollen-grain of Funkia ovata; the knob-like thickenings projecting out- wards are still small; in the older pollen-grain C they are larger; they are arranged in lines united into a FIG. 20.—Ripe pollen-grain of Cichorium Iwtybus; the almost spherical substance of the cell-wall is furnished with ridge-like thickenings united into a net-work; each of these bears thickenings which project still more, in the form of spines arranged like a comb. Fig. 18 bis.—Piece of an annular vessel from the fibro-vascular bundle of the stem of Maize (X 550). h h the thin cell-wall of the vessel, on which the boundary lines of the adjoming cells are clearly seen; r r the annular thickenings of the wall of the vessel; y the inner substance of one of the rings laid open; * the denser layer which extends over the inner side of the ring projecting into the cavity of the cell. (Fig. 23, a-e\ Fig. 24, C, D). Now since this process takes place on both sides of a partition-wall of two cells, a lenticular space is enclosed by the two overarchings, divided in the middle by the original thin cell-wall (Fig. 24, F, w), each half of this pit-cavity communicating with the cell-cavity by a circular opening. When the wood- Akad. der Wissenschaften, Miinchen 1861. On the actual perforation of sieve-plates see Sachs" in Flora. 1863, p. 68, and Hanstein, Die Milchsaftgefasse, Berlin 1864, p. 23 et seq. J 1 The development of these was first accurately recognised by Schacht, De maculis in plantarum vasis, & Bonn i860. ? - . ;. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Sachs, Julius, 1832-1897; Vines, Sydney Howard, 1849-1934. ed. and tr. Oxford, Clarendon press
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
