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 germaiiica, fig. 181, each surface has nearly 12,000 



1, 



Fig. 181. 



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

 the epidermis; b, sfomata cut throuf^h longitudinally; c,c, cells of the 

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

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

 b, cells of the stomafa; c, cells of the parenchyma ■ d, impressions on the epi- 

 dermic cells ; <?, lacunag in the parenchyma. 



Btomata 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 ot from woody fibre. 



Fi 



g- IS2.~-A portion of the epider?ms of the Sugar-cane, shoto'ing ike two kinds o] 

 ceils of vfiuch ii is composed. (Alagnified 200 diameters.) 



