Text-book of botany, morphological and physiological . s recent researches, the mother-cells of the corpuscula(archegonia) arise in the embryo-sac by free cell-formation in the same manneras the first endosperm-cells; but the septa by which the latter are transformed intoa multicellular tissue are not produced. The cells grow, on the other hand, morevigorously, and divide near their apex where they touch the embryo-sac; a large inner [See foot-note to p. 434.] 45^ PHANEROGAMS. (lower) cell is thus formed, the central cell of the archegonium, and an upper smallone, lying next the embryo-sac fro
Text-book of botany, morphological and physiological . s recent researches, the mother-cells of the corpuscula(archegonia) arise in the embryo-sac by free cell-formation in the same manneras the first endosperm-cells; but the septa by which the latter are transformed intoa multicellular tissue are not produced. The cells grow, on the other hand, morevigorously, and divide near their apex where they touch the embryo-sac; a large inner [See foot-note to p. 434.] 45^ PHANEROGAMS. (lower) cell is thus formed, the central cell of the archegonium, and an upper smallone, lying next the embryo-sac from which the neck of the archegonium is formed \In Abies ca?iadensts this neck remains simple and unicellular, and elongatesconsiderably with the increase in size of the surrounding endosperm; but usuallythe original cell which constitutes the neck divides into several cells which eitherlie only in one plane (Figs. ^24 A, d, 325 /, ^), the stigmatic cells, or form severallayers lying one over another (as in Abies excelsa and Pmiis Pinaster). Seen from. Fig. 325.—Juniperus coMityiunis {after Hofmeister). / three archegonia cp close beside one another, in two ofthem the fertilised embryonic vesicles is imbedded in the upper end, (Astigmatic cells,/ pollen-tube (July 28) (X300).// a similar section, e e the endosperm, v v the pro-embryos ; /// lower end of one of the longitudmal rows of cells ofa pro-embryo with the rudmient of the embryo eb; IV longitudinal section of the nucleus kk, e the endosperm, e por-tion of the endosperm that is broken up, p pollen-tube, cp the archegonia, v the pro-embryos (beginning of August)(X80). above the neck appears to form a four-celled, or, in Abies excelsa^ even an eight-celled rosette. The homology of the archegonium corpuscula with the arche-gonium of Vascular Cryptogams, already established by the earlier investigations ofHofmeister, is carried a step further by Strasburger, who discovered the formationalso of a canal-cell. He considers that
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
