78 PLANT LIFE 
vessels, the wood always contains some com- 
paratively undifferentiated tissue cells, such 
oy < 
= 2 
o Q. 
& 5 
> 0 
® :: 
ze G 
a > 
: 2 
Fig. 12.—Diagram to show the bordered pits and how the 
tracheids in the wood of a pine are connected with each 
other. LT, lower tracheid; UT, UT, two upper tracheids; 
BP, bordered pits. At the top a bordered pit is shown 
in section (very highly magnified). 
as are of common occurrence throughout 
the plant body; these, from their ordinary 
