MINUTE STliUCTUEB OF LEAVES. 



109 



Examine another slice from the upper surface. 

 How does the number of stomata in the two cases compare ? 

 Take measurements from the last three sketches with a scale and, 

 knowing what magnifying power was used, answer these questions : ''■ 

 (a) How thick is the epidermis ? 



(6) "What is the length and the breadth of the epidermal cells ? 

 (c) What is the average size of the pulp-cells ? 



sp sp 



Fig. 96. — Vertical Section of the Leaf of the Beet. (Much magnified.) 



e, epidermis ; p, palisade cells (and similar elongated cells) ; i, intercellular spaces ; 

 a, air-spaces communicating with the stomata ; sp, stomata, or breathing-pores. 



136. Uses of the Parts Examined. — It will be most con- 

 venient to discuss the uses of the parts of the leaf a little 



1 The teacher may measure the size with the camera lucida. 



