36 



BOTANY. 



cases, however, are granular protoplasmic bodies (e.g., 

 chlorophyll) present in epidermal cells. 



73. While the epidermis always consists at first of but 

 one layer of cells, it may become split into two or more 



Fio. 21. 



Fig. 22. 



Fio. 21.— Transverse section of epidermis and underlying tissue of ovary of a 

 squash, a. hair of a row of cells; 6 and d. glandular hairs of different ages; 

 c, /, e, hairs in the youngest stages of their development. Magnified 100 times. 



Fig. 22.— a seedling mustard-plant with its single root clothed with root-hairs; 

 the newest (lowermost) portion of the root is not yet provided with root-hairs. 



layers by subsequent divisions parallel to its surface, as in 

 the Oleander and Cactus. 



74. The Hairs of the epidermis originate mostly from the 

 growth of single epidermal cells, and on their first appear- 

 ance consist of slightly enlarged and protruding cells (Fig. 

 21, e, f, c). These may elongate and form single-celled 



