Mosses, Ferns, and Horsetails. 



289 



other by means of the underground parts. Examine the 

 cylindrical stems. Are there any structures growing from 

 the nodes which may be morphologically leaves ? Halve a 

 stem longitudinally from top to bottom and note its con- 

 struction. 



181. Examine the spo- 

 rangia which are borne in 

 cone-like clusters at the 

 tops of the stems. Scatter 

 some of the dry spores on 

 a glass slip and examine 

 with a medium power. 

 Gently breathe on the slip 

 and note the result. Mount 

 some of the spores in a drop 

 of water under a coverglass 

 and examine with a high 

 power. 



FIG. 150. 



A, entire moss plant, the leaf-bearing 

 gametophyte with rhizoids, bearing the 

 sporophyte, i.e. the capsule and its stem ; 

 o, the operculum, which falls off and al- 

 lows the spores to escape ; B, the cap- 

 sule surmounted by the calyptra (c); 

 C, capsules with the fringe of teeth open 

 and closed. In part after KERNER. 



DISCUSSION. 

 MOSSES. 



176. Character of Mosses. 



-The shoot of the moss 



plant is differentiated into 



stem and leaves of very simple construction. Filamentous 

 outgrowths, called rhizoids, anchor the plant to the sub- 

 stratum, and have the absorptive function of the roots of 

 the higher plants (Fig. 150). Because of their simple con- 

 struction and lack of an effective protection against too 

 great transpiration, the mosses are mostly restricted to 

 moist and shady situations, although some species occur 

 in exposed localities, having acquired the power of reviv- 

 ing after long periods of desiccation. The leaves of 



