MINUTE STRUCTURE 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 :1 
(a) How thick is the epidermis ? 
(b) What is the length and the breadth of the epidermal cells ? 
(c) What is the average size of the pulp-cells ? 
Bey ! 
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Fia. 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. 
