70 



THE MICROSCOPIST. 



in various directions, giving its surface a reticulated appear- 

 ance. The form of these reticulations varies in different 



Fig. 23. 



plants : in some they are hexagonal, in others prismatic or 

 irregular. Cuticles may be mounted dry or in fluid. The 

 geranium, oleander, &c., aiford good specimens. See Fig. 40. 



The cuticle of the under side of the leaf of many plants, 

 exhibits under the microscope dark spots among their reticu- 

 lations. These are called stomata, and are the orifices by 

 which a function analogous to respiration in animals is effected. 

 They also serve for the exit of water from the plant by means 

 of evaporation. Plants destitute of stomata, as the South 

 American Cacti, &c., will remain in a hot and dry atmosphere 

 without losing their moisture. The form, number, and ar- 

 rangement of the stomata vary in different plants. 



Cellular Tissue is the first and most generally developed 



