CRYPTOGAMS 341 



relationships and their order of succession in the evolutionary 

 scale be made intelligil)le. 



VI. MOSSES 



Material. — One of the most widely distributed of mosses is the 

 Sphagnum, or peat moss, so generally used by florists in packing plants for 

 shipment, and it can be obtained from them at almost all times. It is 

 rather difficult, however, to find spechnens with the fruiting organs, since 

 they are rarely to be met with except in late autumn or early spring. 

 Other common forms are Polytrichum, Funarin, and Mmutn, any of which 

 will meet all essential conditions of the study outlined in the text. 



396. The protonema or thallus stage. — In mosses the 

 sexual, or gametophyte generation differs from that of 

 liverworts in undergoing two phases. The germinating 

 cells of the sporophyte do not develop immediately into 

 the leafy stem, which is the typical gametophyte of true 

 mosses, but produce first a filamentous, creeping structure 



Figs. 482, 483. — Protonoma of a moss: 482, germinating spore; 483, protonema; 



kn, buds ; r, rhizoids ; s, spore. 



called the protonema (Fig. 483), that spreads over the 

 ground and forms the tangled green felt usually observed 

 where mosses are growing. Place a few of these filaments on 

 a slide in water, and examine under the microscope. Do 

 they remind you of any of the forms of alga3? Look near 



