96 PRACTICAL BOTANY. 



colourless sheath of cells without intercellular spaces. 

 At the lower limit of the section lies 



5. The lower Epidermis, which resembles (1) in 

 general character; but differs in having numerous 

 Stomata. Note the appearance presented where the 

 two Guard cells of a stoma have been cut transversely, 

 and observe carefully 



a. The form and position of the two guard cells. 



I. The cavity or intercellular space between them 

 (the Pore) ; this leads into 



c. The large, intercellular space (Respiratory cavity) 

 in the tissue beneath the stoma. 



d. In the sections stained with Schulze's solution or 

 with fuchsin, note the continuity of the cuticle round 

 the guard cells, into the pore of the stoma. 



IV. Cut tangential sections from the upper and 

 under surfaces of the leaf, and mount separately with 

 the external surface in both cases uppermost. 



The cells of the upper epidermis are tabular, with 

 sinuous outline ; the surface has a granular appear- 

 ance (explained by the granular cuticularised layers 

 observed in transverse sections) ; the lateral walls are 

 pitted; contents colourless; no stomata. 



The cells of the lower epidermis are similar to 

 the above ; but stomata are numerous ; they have 

 no definite arrangement. Note the two sausage-shaped 

 nucleated guard cells, inclosing the pore ; they contain 

 chlorophyll. 



(For development of stomata, cf. Hyacinth, p. 117.) 



V. No Subsidiary cells are found in the Cherry 

 Laurel. The leaves hitherto studied are of the bifa- 

 cial type, i.e. the difference of the upper and lower 



