. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. CYCADALES 23 elusion; Treub ^* in 1884 stated positively that there is no such cell in Gycas circinalis. Until Ikeno's demonstration in 1896, therefore, the absence of such a cell in the Cycads was generally accepted. It is important to note that the development of a group of archegonia checks the growth of the vegetative tissue of the gametophyte in that region, and the adjacent regions continu- ing to grow, the archegonial region is left at the bottom of a pit- like depression, which may be called the arche
. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. CYCADALES 23 elusion; Treub ^* in 1884 stated positively that there is no such cell in Gycas circinalis. Until Ikeno's demonstration in 1896, therefore, the absence of such a cell in the Cycads was generally accepted. It is important to note that the development of a group of archegonia checks the growth of the vegetative tissue of the gametophyte in that region, and the adjacent regions continu- ing to grow, the archegonial region is left at the bottom of a pit- like depression, which may be called the archegonial chamber, or " endosperm cavity," as Warming has called it. This cham- ber is full of liquid during fertilization, and at the bottom of it the necks of the archegonia open (Fig. 18). Occasionally two of these chambers have been observed, each with its group of archegonia. THE MALE GAMETOPHYTE The male gametophyte begins with the reduction division of the spore mother cell, which seems to have received no special attention in Cycads. The organization of the tetrad by successive division, accom- panied by a peculiar chambering of the mother cell, has been described in detail by Juranyi ^ for C'eratozamia longifolia, and by Treub ^^ for Zamia muricata (Fig. 21). With the appearance of the nuclear plate in the first division, a ring of thickening develops upon the outer surface of the wall of the mother cell in the plane of the plate. Proceeding from this ring of thickening, a heavy wall develops between the two daughter cells. Juranyi thought that the nuclear plate disappears, and that the heavy wall is formed by growth at the free inner edge of the ring. Treub dissents from this view, and, although he could not demon- strate the fact on account of the abundant starch grains, thinks that the nuclear plate persists and gradually thickens, the thick- ening proceeding from the peripheral ring toward the center. The latter view seems to be the more reasonable one. The
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