154 THE MICROSCOPIST. 



In lichens, the apothecia form projections from the thal- 

 lus, or general expansion produced by cell-division. A 

 vertical section shows them to contain asci or spore-cases 

 amid straight filaments, or elongated cells called para- 

 physes. 



The fronds of Hepaticce or liverworts bear stalks with 

 shield-like disks, which carry antheridia, and others with 

 radiating bodies bearing archegonia, which afterwards 

 give place to the sporangia or spore-cases. The spores 

 are associated with elaters, or elastic spiral fibres, which 

 suddenly extend themselves and disperse the spores. 



The Characece. are often incrusted with carbonate of 

 lime, which may be removed with dilute sulphuric acid. 

 The motion of the bioplasm in the cells of the stem is 

 often well seen. The cells in which the spiral filaments 

 or antheridia are developed, are strung together like a 

 row of pearls. The position and construction of the spores 

 also should be examined, as well as the mode of growth 

 in the plant by division of the terminal cell (Plate XI, 

 Fig. 113). 



Stems of mosses and liverworts should be examined by 

 means of transverse and longitudinal sections. Similar 

 sections through the half-ripe fruit of a moss will show 

 the construction of the fruit, the peristome, the calyptra, 

 etc. The ripe spores may be variously examined dry, in 

 water, in oil of lemons, and in strong sulphuric acid. The 

 capsules or urns of mosses are not now regarded as their 

 fructification, but its product. 



The true antheridia and pistillidia are found among the 

 bases of the leaves, close to the axis. The fertilized " em- 

 bryo-cell " becomes gradually developed by cell-division 

 into a conical body or spore-capsule, elevated on a stalk. 

 The peristome, or toothed fringe, seen around the mouth 

 of the urn when the calyptra or hood, and operculum or 

 lid, are removed, furnishes a beautiful object for the bi- 

 nocular microscope. 



