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 



prim 



Fie. 199. Protonema of a Moss. 



prim, primary shoot; h, a young root-hair; pZ, young moss-plant; br, 

 branches olprimary 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 tliin-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. 



