CRTPTOGAMIC LABOEATORT STUDIES 259 



arrangement of the leaves at the summit. The sporogonia are mature 

 later. Preserve in alcohol, if necessary. Other mosses (e.(/. Milium) 

 will serve. The protonema may be found in greenhouses aud on soil 

 where moss is growing. 



390. Fern. — Prothallia are easiest got in greenhouses. They may 

 best be grown (by the florist) on potsherds. The smaller prothallia 

 are likely to have antlieridia alone. For the spores, use preferably 

 some Aspidiuui, taken when tlie sori are youngish. If necessary 

 preserve this material in alcohol. In the JMaidenliair Fern the sori 

 are covered by the recurved leaf margin — not an indusiura. — If 

 smallish prothallia, which have not been wet for some time, are placed 

 in a drop of water on a slide, the antherozoids are likely to be seen ; 

 use a low power of the compound microscope. 



396. Selaginella, from greenhouses, in fruit in early spring (some 

 species at other times). .S. rupealris is found in dr}' situations (as 

 bare hilltops) at the edge of ledges in poor soil. It loolcs at a 

 distance like a stiff, coarse moss. 



400. Lycopodium is the "ground pine" used for Christmas decora- 

 tions. In fruit in late summer. 



402. Equisetum arvense is common on railroad bank.s, the fertile 

 shoots appearing in early May, the vegetative shoots later. 



