. A text-book of botany for secondary schools. Botany. LIVERWORTS 169 the back of the thallus (Fig. 163). These bodies are round and flat (biscuit-shaped) and many-celled, and falling out of the cup they start new thallus bodies. Although the thallus body produces no spores, it does produce sex-organs. In Marchantia, long, erect, stem-like branches arise from the thallus, bearing at their summits conspicuous disks that contain the sex-organs. The disks containing antheridia are lobed or scalloped (Fig. 163); while those containing the egg-producing organs are star- shaped (Fig. 165). The two k
. A text-book of botany for secondary schools. Botany. LIVERWORTS 169 the back of the thallus (Fig. 163). These bodies are round and flat (biscuit-shaped) and many-celled, and falling out of the cup they start new thallus bodies. Although the thallus body produces no spores, it does produce sex-organs. In Marchantia, long, erect, stem-like branches arise from the thallus, bearing at their summits conspicuous disks that contain the sex-organs. The disks containing antheridia are lobed or scalloped (Fig. 163); while those containing the egg-producing organs are star- shaped (Fig. 165). The two kinds of disks are not found on the same plant. 93. The antheridium. — The sperm-producing organ is called an antheridium, but it is very different from the antheridia of the Thallophytes. Instead of be- ing a single cell, it is a stalked, club-shaped or globular, many- celled structure (Fig. 164). A single layer of cells forms the covering, and within it there is a closely packed mass of small cells, each one of which pro- duces a sperm. The sperm is a very small cell with two long cilia, and these small biciliate sperms are one of the distinguishing features of the liverworts and their allies. 94. The archegonium.—The egg-producing organ is called the archegonium, and it is very different from the oogonium of the Thallophytes. Instead of being a single cell, it is a manj^-celled structure, shaped like a flask with a long neck, and within the bulbous base the single egg is formed (Fig. 165, B, and Fig. 166). To this neck the swimming sperms are attracted; they enter and pass down. Fig. 164.—Marchantia: antheritli- um and two sperms. — After Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928. New York, D. Appleton
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