TISSUE-DIFFERENTIATION 



125 



FIG. 45. Stereogram of the leaf of an Iris : e, epidermis ; c, cuticle ; 

 p, palisade cells filled with chlorophyll-bodies ; col, collecting cells ; 

 conv, conveying cells which assist in the transfer of the synthesized 

 sugars from their place of origin to the veins ; sh, conducting sheath of 

 vein ; h, wood of vein ; b, bast or woody fibrous portion of vein ; a, air- 

 space ; s, stoma ; g, guard cells. (Osterhout.) 



