DESCRIPTION OF PLATE IV. 



Fig. 1. — Hicoria ovala (shagbark hickory): cross section showing very thick- 

 walled wood fibres and distinct tangential lines of wood parenchyma; large pores 

 with tyloses. 



Fig. 2. — Diospyros virginiana (persimmon) : cross section showing rather in- 

 distinct tangential lines of wood parenchyma; pores without tyloses. 



Fig. 3. — Hicoria pecan (pecan hickory) : tangential section showing very 

 irregular rays, three large calcium-oxalate crystals, and numerous wood-paren- 

 chyma fibres. 



Fig. 4. — Diospyros virginiana: tangential section showing fairly uniform 

 rays in storied arrangement. Crystals visible, but very small. 



Fig. 5. — The same: radial section showing vessel segments, heterogeneous 

 rays, wood-parenchyma fibres, and wood fibres in tier-like arrangement. 



Fig. 6. — Juglana nigra (black walnut) : radial section showing rays, large 

 vessel with tyloses, wood-parenchyma fibres, chambered-parenchyma fibres with 

 crystals, and wood fibres. 



