44 



BOTANY. 



times the terminal cell of a hair becomes changed into a 

 secreting cell and manufactures a gummy or resinous sub- 

 stance. Such hairs are called Glandular Hairs and are 

 common on many plants (Figs. 36, 38). 



77. Breathing-pores {stomata; singular, stoma) consist, 

 in most cases, of two specially modified chlorophyll-bear- 

 ing cells, called the guard-cells, which have between them 

 a cleft or slit passing through the epidermis (Fig. 39). 

 These openings are always placed directly over interior 

 intercellular spaces. 



Fig. 29.— a bit of the epidermis of Wild Cucumber (Bchinocystis), show- 

 ing breathing-pores at s, s, s. At g, », the epidermal cells are irregular • at 

 ■B, over a vein, they are more regular. Magnified 250 times. 



78. They occur on aerial leaves and stems most abun- 

 dantly, being sometimes exceedingly numerous, and are 

 exceptionally found elsewhere, as on the parts of the flow- 

 ers. On submerged or undergound stems and leaves they 

 are found in less numbers, and from true roots they are 



