Elementary botany . Fig. 262. Marchantia polymorpha, showing origin of the thallus project forward andcf gametophore. overlap in advance of the stalk. It is sometimes necessary to tear these overlapping edges apart to see thereal origin of the gametophore. But in quite old plants these expandedportions are farther apart and show clearly that the stalk arises from themidrib below and arches upward in the sinus, as in fig. 262. CHAPTER XXIV. LIVERWORTS CONTINUED. 488. Sporogonium of marchantia.—If we examine the plantshown in fig. 181 we shall see oval bodies which stand out be-. Fig. 263. Arche
Elementary botany . Fig. 262. Marchantia polymorpha, showing origin of the thallus project forward andcf gametophore. overlap in advance of the stalk. It is sometimes necessary to tear these overlapping edges apart to see thereal origin of the gametophore. But in quite old plants these expandedportions are farther apart and show clearly that the stalk arises from themidrib below and arches upward in the sinus, as in fig. 262. CHAPTER XXIV. LIVERWORTS CONTINUED. 488. Sporogonium of marchantia.—If we examine the plantshown in fig. 181 we shall see oval bodies which stand out be-. Fig. 263. Archegonial receptacles of marchantia bearing ripe of the sporogonium projects outside, while the stalk is attac The attached tothe receptacle underneath the curtain. In the left figure two of thecapsules have burst and the elaters and spores are escaping. tween the rays of the female receptacle, supportedon short stalks. These are the sporogonia, orspore-cases. We judge at once that they are quitedifferent from those which we have studied inriccia, since those were not stalked. We can seethat some of the spore-cases have opened, the wallsplitting down from the apex in several lines. Thisis caused by the drying of the wall. These tooth-like divisions of the wall now curl backward, andwe can see the yellowish mass of the spores in slow motion, 231 232 MOEPHOLOG Y. falling here and there. It appears also as if there were twistingthreads which aided the spores in becoming freed from thecapsule.
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