336 



THE MICROSCOPE. 



by minute openings termed Stomata, which are bordered by 

 cells of a peculiar form, distinct from those of the cuticle. 

 In Iris germanica, fig. 181, each surface has nearly 12,000 



Fig. 181. 



2. 



Portion of a vertical section of the Leaf of the Iris: a, a, elongated cells of 

 the epidermis ; b, stomata cut through longitudinally ; c, c, cells of the 

 parenchyma ; d,d, colourless tissue of the interior of the leaf. 2, Portion of 

 leaf of Iris germanica, torn from its surface ; a, elongated cells of the cuticle ; 

 b, cells of the stomata; c, cells of the parenchyma : d, impressions on the epi- 

 dermic cells ; e, lacunae in the parenchyma. 



stomata in every square inch ; and in Yucca each surface 

 has about 40,000. 



The structure of the leaf of the common Iris shows 

 a central portion, formed by thick-walled colourless tissue, 

 very different from ordinary leaf-cells or from woody fibre. 



Fig. 1S2.— A portion of the epidermit of the Sugar-cane, showing the two kinds oj 

 cells of which it is composed. (Magnified 200 diameters.) 



