558 



ECOLOGY 



FIG. 800. A cross section through a 

 stoma from a leaf of the carnation (Dianthus 

 Caryophyllus) ; by reason of the heavy cu- 

 tinization of the outer epidermal wall (w) t 

 the stoma lies below the surface level of the 

 leaf; note the thin places (h) above and 

 below the dorsal wall (d) of the guard cell 

 () representing the so-called hinges which 

 are thought to facilitate guard-cell move- 

 ment; the chamber above the stoma is 

 called a stomatal pit; general lettering as 

 in fig. 795; highly magnified. 



FIG. 802. A cross sec- 

 tion through a stoma from 

 the under leaf surface of the 

 nipa palm (Nipa fruticans), 

 showing the tortuous pas- 

 sageway (M), which must 

 be traversed by transpiring 

 water that passes from the 

 stomatal cavity (c) to the 

 exterior at e; g, guard cell; 

 highly magnified. From 

 BOBISUT. 



FIG. 80 1. A cross section through a stoma from a leaf of the India-rubber tree 

 (Ficus elastica) ; the stoma lies below the surface level of the leaf by reason of its position 

 beneath the subsidiary cells (6), which have projecting ridges (r f ) partially enclosing the 

 pit (p); the dorsal wall (d) of the guard cell is so braced by the thick walls of the ad- 

 joining cells that guard-cell movement must be slight; note that the epidermis (e) con- 

 sists of three cell layers and that the cuticle (z) is highly developed; general lettering 

 as in Fig. 795; highly magnified. 



