18 THE VEGETABLE KINGDOM. 



Tradescantia , . . 2,000 upper surface 

 Lilac . . .160,000 under surface 



Vine ... 13,000 under surface. 



The stomata are generally largest upon succulent plants, 

 and abound on the under side of all leaves except grasses 

 and upright leaves, such as the Iris and Tradescantia, where 

 they are found equally on both sides. 



CUTICLE OF YUCCA. 



In the cuticle of Yucca the stomata are bounded by four 

 cells, and are themselves somewhat quadrangular : there are 

 about 40,000 of them in one square inch. The plant is a 

 native of Peru ; called also common Adam's needle, bearing 

 a handsome flower in panicles on a stem eight or ten feet 

 high when in its native soil; but in British gardens it 

 scarcely reaches three feet high. 



CUTICLE OF ALOE. 



The cells are somewhat different in shape, though the 

 stomata are also bordered by four cells : they are more 

 oblong, very prettily disposed, but require a power of 200 

 diameters to observe properly. First use the i-inch, and 

 then the ?-inch. 



CUTICLE OF DEUTZIA SCABRA. 



This is a polariscope object. 



The cuticle is siliceous (see Indian Corn), and the wavy 

 outlines of the cells and the starry clusters of siliceous 

 hairs are very beautiful. "When gathered from the tree, 

 these stars are white upon the green cuticle, and those of 

 the upper surface are many-rayed, whereas those of the 

 lower surface have usually but four or five rays. 



This leads us to consider the use of those abundant hairs 

 which clothe the living plant. They serve two purposes 

 for warmth to the tender bud, or for attracting moisture. 

 On many plants they rise up towards evening and catch 

 the falling dew ; then bending downwards at noontide they 

 form a close layer over the cuticle, and give it a protecting 



