. Text-book of botany, morphological and physiological. Botany. FILICINEffi. 411 of which is subsequently developed a cylindrical vermiform shoot, which grows erect underground, is rarely and slightly branched, and elongates by means of a single apical cell. When the apex appears above ground and becomes green, it forms lobes and ceases to grow. The tissue of this prothallium is differen- tiated into an axial bundle of elongated, and a cortex of shorter parenchymatous • cells, and the surface is clothed with root-hairs. With a transverse diameter of \ to 1 \ lines, it attains a length of from
. Text-book of botany, morphological and physiological. Botany. FILICINEffi. 411 of which is subsequently developed a cylindrical vermiform shoot, which grows erect underground, is rarely and slightly branched, and elongates by means of a single apical cell. When the apex appears above ground and becomes green, it forms lobes and ceases to grow. The tissue of this prothallium is differen- tiated into an axial bundle of elongated, and a cortex of shorter parenchymatous • cells, and the surface is clothed with root-hairs. With a transverse diameter of \ to 1 \ lines, it attains a length of from 2 lines to 2 inches. The pro- thallium of Botrychium Lunaria is. according to Hofmeister, an ovoid mass of firm cellular tissue, the greatest diameter of which does not exceed \ line, and is often much less (Fig. 287, A). It is light brown externally, yellowish white internally, and provided on all sides with sparse moderately long root-hairs. These prothallia are monoecious; each one produces a number of antheridia and archegonia, which are distributed with tolerable uniformity over the whole of its upper surface, with the exception, in O. pedunculosum, of the small primary tuber; in Botrychium it is the upper side which chiefly bears antheridia. The Antheridia are cavities in the tissue of the prothallium covered externally by a few layers of cells, and in Ophioglossum only slightly projecting beyond the. FIG. ^.—Botrychium Lunaria; A longitudinal section of prothallium (X 50), ac an archegonium, an an antherU dium, tv root hairs; B longitudinal section of the lower part of a young plant dug up in September (X20); st stem, b b' b'1 leaves (after Hofmeister). surface. In this genus the mother-cells of the antherozoids originate by repeated divisions from one or two cells of the inner tissue (covered externally by one or two layers of cells); they form a mass of tissue of roundish form, and, as in Botrychium, give rise to the antherozoids, which are similar in form to those
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
