Archive image from page 324 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana05todd Year: 1859 Section of naked nucleus of Hippuris vulgaris at an early stage, about 150 diam. The embryo-sac is seen as a large central nucleated cell. (Unger.) than the rest, from which it is further distin- guished by its containing a free vesicular nu- cieolated cell-nucleus and granular fluid. This cell, the embryo sac, rapidly enlarges, and at the same time assumes an elongated oval form. A number of vesicles of various size are de- veloped at the same time, at its m
Archive image from page 324 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana05todd Year: 1859 Section of naked nucleus of Hippuris vulgaris at an early stage, about 150 diam. The embryo-sac is seen as a large central nucleated cell. (Unger.) than the rest, from which it is further distin- guished by its containing a free vesicular nu- cieolated cell-nucleus and granular fluid. This cell, the embryo sac, rapidly enlarges, and at the same time assumes an elongated oval form. A number of vesicles of various size are de- veloped at the same time, at its micropyle extremity, all of which disappear some time before the scattering of the pollen. Shortly after this has taken place several new cells are formed, one of which, situated towards the upper end of the sac, begins at once to lengthen, and is finally converted into a tube closed at both extremities (germ-cell). The rest arrange themselves in vertical series, so as to form a continuous tissue (the endo- sperm), which completely occupies the lower part of the sac. After this, in consequence, as may be presumed, of the contact of the pollen tube with the membrane of the sac, the germ-cell is divided by a transverse septum Unger, Botanische Beobachtungen, Entwick. des Embryos von Hippuris vulgaris. Bot. Zeitung, ]>, p. 329. Sanderson, On the Embryogeny of Hippuris vulgaris. Trans, of Bot. Soc. of Edinburgh, Feb. 1850. Upper end of embryo-sac of the same as observed immediately before impregnation, 250 diam. The tubular germ-cell, the lower end of which is embedded in the nucleated cells of the endosperm, occupies its axis. latter, which is the parent cell of the embryo, is divided by a vertical septum into two hemispheres. In these two new septa are formed, also vertical, but at right angles to
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