56 



PLANT LIFE. 



Fig. 68. — Transverse section of the stem of Bryuin roseum. In the center the 

 small cells make a central strand, the "conducting tissue "; the surface cells form 

 an epidermis; the next three rows within also have thick walls and strengthen the 

 stem; w, rhizoids arising from epidermis. Magnified 50 diam. — After Sachs. 



Fig. 69. 



Fig. 



70- 



Fig. 69. — A, leaf of a moss (Funaria Americana), showing central rib. Magnified 

 about 40 diam.; /?, upper portion of the same leaf, highly magnified, showing 

 single layer of cells forming the blade and the narrower cells of the thick rib. — 

 After Sullivant. 



Fig. 70 — Tip of leaf of a moss (Oligotrichum aligtrum), showing the thickened 

 rib, and the plate like ridges on blade and rib greatly increasing the surface of 

 nutritive tissue, Magnified about 75 diam.— After Sullivant, 



