Text-book of botany, morphological and physiological . nded part which subsequently developes would be theoosphere, and the upper appendage the canal-cell, which is in this case onlyseparated from the former after impregnation. The very rare occurrence of thefiliform apparatus in Angiosperms can scarcely be brought forward as an objectionto the explanation; since in this case, as in the antipodal cells, we have to dowith an organ which has become rudimentary, and the occurrence of such organsis commonly observed to be very variable and inconstant. In the enormousmajority of Monocotyledons and
Text-book of botany, morphological and physiological . nded part which subsequently developes would be theoosphere, and the upper appendage the canal-cell, which is in this case onlyseparated from the former after impregnation. The very rare occurrence of thefiliform apparatus in Angiosperms can scarcely be brought forward as an objectionto the explanation; since in this case, as in the antipodal cells, we have to dowith an organ which has become rudimentary, and the occurrence of such organsis commonly observed to be very variable and inconstant. In the enormousmajority of Monocotyledons and Dicotyledons the filiform apparatus of the em-bryonic vesicles is wanting, the number of these latter being almost invariably two,rarely three. They usually lie obliquely one over the other, one closely attachedto the apical prominence of the embryo-sac, the other situated lower down andsideways, but adpressed to the former by its bit)ad surface; both adhering by theirperipheral end to the wall of the sac. The fertilising pollen-tube usually, as Hof-. FlG. -^.—Futikia cordata; A apex of the embryo-sac e, covered with a layer of cells belonging to. the nucleus KK, x theembryonic vesicle which is incapable of fertilisation, o the peculiarly shaped oosphere with its nucleus ; B, C oospherebefore, D, E after the first division ; F the spherical pro-embryo with the two-celled rudimentary embryo (Xsoo). meisters and Schachts drawings show, perhaps always, the apical embryonicvesicle (,^, ji); but this does not then undergo further development, but dis-appears, while the one which lies lower down and at the side (0), and which is nottouched at all by the pollen-tube, produces the pro-embryo, and subsequently theembryo. It appears therefore as if one of the two embryonic vesicles assume thefunction of the filiform apparatus or the canal-cell, while the other represents theoosphere. Sometimes even one embryonic vesicle is decomposed before impregna-tion takes place, as i
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
