PLANT LIFE. 



FIG. 68. Transverse section of the stem of Bryum 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.; B, 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 (Oligotricku-m aligerutii)^ 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. 



