ELEMENTS OF APPLIED MICROSCOPY. 



swellings at intervals along their course are also present 

 in birchwood. 



The small, broad cells of the fibrovascular bundles 

 are more characteristic. In birch they are very numer- 



A B C 



Fig. 41. — Cells of Steaw. (After Herzberg.) 240 diameters. 



ous, and are dotted with minute pores arranged in rows 

 at right angles to the long axis of the cell (Fig. 40). The 

 distribution of these pores is somewhat irregular. At 

 the ends of the cell the cross-hatched transverse walls 

 are sometimes seen. In poplar the cells of this type are 



