. Botany for high schools and colleges. Botany. 34G BOTANY. 450.—The sexual organs are situated in depressions in the upper side of the thallus, or upon the sides or ends of the stems, and are surrounded by peculiarly developed leaves {2)crichcdiu7}i) in the leaf-bearing forms. antheridium is a more-or less globular—usually stalked—body, which arises from a single cell (hence mor- phologically a trichome) by the repeated subdivision of its terminal cells. Its outer wall consists of a single layer of cells {G, Fig. 231, tu), and its cavity is filled with a large number of sperm-cells,
. Botany for high schools and colleges. Botany. 34G BOTANY. 450.—The sexual organs are situated in depressions in the upper side of the thallus, or upon the sides or ends of the stems, and are surrounded by peculiarly developed leaves {2)crichcdiu7}i) in the leaf-bearing forms. antheridium is a more-or less globular—usually stalked—body, which arises from a single cell (hence mor- phologically a trichome) by the repeated subdivision of its terminal cells. Its outer wall consists of a single layer of cells {G, Fig. 231, tu), and its cavity is filled with a large number of sperm-cells, each of which contains a single spermatozoid. The sperm-cells escape by the breaking of the antheridium wall, and in the water in which this always takes place they rupture, and the spermatozoids are set free. Each spermatozoid is a spirally curved slender thread of. Fig. 233. Fig. 234. Fig. 233.—Development of the antheridia of Marchantia iwlymorpha, in 'c section of a young antheridial disc, r, the growing anterior margin of the disc; from r to the left are shown the antheridia (a, a, «, a) in four stages of development; at sjj, sp, sp, are shown the stages of development of the stomata above the air cavities be- tween the antheridia. X 300.—After Hofmeistt r. Fig. 234.—A, longitudina-l section of the apex of the thallus of Riccia glauca. ar^ archegonium; c, germ-cell. B. the unripe sporogonium, sg, surrounded by the calyp- tra, which still bears the neck of the archegonium, ar. A X 560 ; £ X 300.—After Hofmeister. , . protoplasm, provided at the anterior end with two long ciha (D, Fig. 231). 452.—In some cases the antheridia are developed singly upon the upper surface of the thallus, as in Biccia (Fig. 232). In this particular case the antheridium is developed directly from an epidermal cell {A, Fig. 232, a), and so is ^t first external; it, however, soon becomes overarched. Please note that these images are extracted from scanned page images that may have
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