STRUCTURE OF THE STEM 



peculiar pits. These pits, when young, are shaped much 

 like two perforated watch-glasses, placed against a piece 

 of cardboard, with their concave sides toward each other 



FTG. G3. FIG. 64. FIG. 65. 



FIG. 63. Part of a Sieve-Tube from Linden. 

 s, sieve-plates on the cell-wall, (x about 900.) 



FIG. 64. Parts of Sieve-Tubes as found in Plants of the Gourd Family. 

 (Greatly magnified.) 



s, s, a sieve-plate seen edgewise ; above it a similar one, surface view. 



FIG. 65. Cross-Section of Fir Wood. 

 s, a resin passage ; m, medullary rays. (Much magnified.) 



