248 PHYLUM VIII. BRYOPHYTA 



Laboratory Studies, (a) Look for Riccias on the wet 

 ground by the sides of ponds and slow streams from midsummer 

 to fall. Make careful vertical sections for structure of the 

 gametophyte, at the same time looking for the sexual organs 

 and the imbedded sporophyte. 



(b) Study Anthoceros for gametophyte, and cylindrical spor- 

 ophj'tes. In the latter find stomata, spores and simple elaters. 

 Anthoceros may be obtained from the South (Gulf states) for 

 study in early spring. 



(c) Collect specimens of the Great Liverwort (Marchantia) 

 which may be found in fruit in midsummer. Note that one 

 plant produces the antheridial branches, which have flat disks, 

 and another produces the archegonial branches, which have 

 lobed disks (''receptacles"). Note the cups, with contained 

 brood masses (gemmae). 



(d) Examine the upper surface of a plant with a low power 

 of the microscope, and note the round ''stomata." Next strip 

 off some of the epidermis, mount in alcohol, and study with a 

 high power. 



(e) Make longitudinal sections . of the plant through its 

 thickened central rib, and observe the elongated cells, with 

 foreshadow fibro-vascular bundles. 



(/) Make vertical sections of the antheridial disk, mount in 

 water, and study the antherids. By repeated trials sperms 

 also may be seen. 



(g) Make similar sections of the archegonial disk, and study 

 archegones. By taking older specimens the sporophytes, 

 spores, a<nd elaters may be studied. For the latter, mount in 

 alcohol and afterward add a little potassium hydrate. 



(h) Examine the bark of trees for small brownish Scale 

 mosses. Mount a bit of one in alcohol, afterward adding potas- 

 sium hydrate, and study for structure of the gametophyte. 

 In the spring the minute splitting spore cases may readily be 

 found. 



Class MUSCI. Mosses 



437. The gametophyte in this class is a leafy multi- 

 lateral stem, rarely bilateral. It is fixed to the soil or 

 other support by root-hairs (rhizoids) which grow out 

 from the sides of the stem. The leaves are usually 



