CHAP, i.] PLANT ARCHITECTURE. 39 



forceps and examined in water under the microscope, 

 the origin and development of the stomata may be easily 

 followed. 



The cells of the epidermis as seen from the surface 

 are brick- shaped, their long diameter being arranged in 

 the direction of the length of the leaf. The stomata 

 originate as follows. A certain epidermal cell is divided 



Fig. ii. A fragment of epidermis from the under surface of a leaf 

 of Euonymus japonica, showing four stomata; sp, guard-cells of the 

 stoma. (Highly magnified.) 



into two parts by a wall that is always formed at right 

 angles to the length of the leaf. One of the small, or 

 daughter-cells thus formed, undergoes no further de- 

 velopment, but loses its protoplasm, becomes cuticularized, 

 and forms an ordinary epidermal cell ; the other daughter- 

 cell, that is, the other half of the epidermal cell, now 

 called the mother-cell of the stoma, retains its protoplasm 



