THE CELL-WALL. 



Bordered Pits. This condition may be further complicated by the 



existence of a lenticular depression between the contiguous walls of pitted 



cells, as in the wood of Comferae (fig. 537). The outline of this depression 



ives the appearance of a circle surrounding the central pit the circle 



eing due to the greater thickness of secondary growth in that situation. 



.1 , . i ^ * 3 *.!** 



Fig. 537. 



Pits or " GUnde" of Convene. 



Magn. 10X) diwu. 



tion which is the primary deposit of the two cells. The lenticular cayity 



is formed by the resorption of this deposit, and a communication esta- 



blished between the two adjacent cells. These areolated pits (or i?te, 



- hacht calls them) are not, as was once supposed, confined to the 



ra? ; but they are universally found throughout that group with a 



regularity of disposition and constancy of occurrence not known else- 



re. 



Lattice or Clathrate Cells, Sieve disks. A further compli- 



cation of the pitted structure has been described by Von Mohl 



a- uA'iirrm^ iu the vctsa propria of the vascular bundles of Mono- 



!bn$,and in the thin-walled cells, layers of which alternate 



