=488. Sporogonium of marchantia.=—If we examine the plant shown in fig. 181 we shall see oval bodies which stand out between the rays of the female receptacle, supported on short stalks. These are the sporogonia, or spore-cases. We judge at once that they are quite different from those which we have studied in riccia, since those were not stalked. We can see that some of the spore-cases have opened, the wall splitting down from the apex in several lines. This is caused by the drying of the wall. These tooth-like divisions of the wall now curl backward, and we can see the yellowish mass of the spores in slow motion, falling here and there. It appears also as if there were twisting threads which aided the spores in becoming freed from the capsule. [Illustration: Fig. 264. Section of archegonial receptacle of Marchantia polymorpha; ripe sporogonia. One is open, scattering spores and elaters; two are still enclosed in the wall of the archegonium. The junction of the stalk of the sporogonium with the receptacle is the point of attachment of the sporophyte of marchantia with the gametophyte.] [Illustration: Fig. 265. Elater and spore of marchantia. _sp_, spore; _mc_, mother cell of spores, showing partly formed spores.] =489. Spores and elaters.=—If we take a bit of this mass of spores and mount it in water for examination with the microscope, we shall see that, besides the spores, there are very peculiar thread-like bodies, the markings of which remind one of a twisted rope. These are very long cells from the inner part of the spore-case, and their walls are marked by spiral thickenings. This causes them in drying, and also when they absorb moisture, to twist and curl in all sorts of ways. They thus aid in pushing the spores out of the capsule as it is drying. =490. Sporophyte of marchantia compared with riccia.=—We must recollect that the sporogonium in marchantia is larger than in riccia, and that it is also not lying in the tissue of the thallus, but is only attached to it at one side by a slender stalk. This shows us an increase in the size and complex structure of this new phase of the plant, the _sporophyte_. This is one of the very interesting things which we have to note as we go on in the study of the higher plants. [Illustration: Fig. 266. Marchantia polymorpha, archegonium at the left with egg; archegonium at the right with young sporogonium; _p_, curtain which hangs down around the archegonia; _e_, egg; _v_, venter of archegonium; _n_, neck of archegonium; _sp_, young sporogonium.] =491. Sporophyte dependent on the gametophyte for its nutriment.=—We thus see that at no time during the development of the sporogonium is it independent from the gametophyte. This new phase of plants then, the sporophyte, has not yet become an independent plant, but must rely on the earlier phase for sustenance.