CRYPTOGAMS 341 
relationships and their order of succession in the evolutionary 
scale be made intelligible. 
VI. MOSSES 
Marertau. — One of the most widely distributed of messes is the 
Sphagnum, or peat moss, so genérally 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 specimens with the fruiting organs, since 
they are rarely to be met with except in late autumn or early spring. 
Other common forms are Polytrichum, Funaria, and Mnium, 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 
Fras. 482, 483. —Protonema 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 alge? Look near 
