274 ESSENTIALS OF BOTANY 
353. The Protonema. — Look in the neighborhood of patches of 
moss for a felt-like network of green threads covering the ground. 
It is most readily found on the earth of flower-pots in greenhouses. 
Mount some filaments in water and examine with m.p. Compare 
with Fig. 199. Invert a patch of moss in a plate with water, cover 
Fic. 199. Protonema of a Moss. 
prim, primary shoot; h, a young root-hair; pl, young moss-plant; 67, 
branches of primary shoot. 
with a bell-glass in a sunny place, and note any changes that may 
after some weeks occur in the appearance of the exposed rhizoids. 
Explain. 
354. Minute Structure of the Gametophyte, Vegetative Portion. — 
Examine with m.p. a microtome section of the stem near the base. 
Note: : 
(a) The central strand of small cells. 
(b) Intermediate tissue of larger thin-walled cells, followed near 
the exterior by thicker ones. 
(c) The epidermis. 
(d) The rhizoids (not present on the upper parts of the stem) 
springing from the epidermis. Draw. 
Examine a leaf with 2-inch objective and then with m.p. Note: 
(a) The midrib, of mechanical cells. 
