PLATE LXVL 



Fig. 5. Cross section of a leaf stained with methylene blue. Stippling 

 indicates cells whose contents stained a deep blue: a, guard cells; b, epi- 

 dermal cell beneath guard cell; d, spongy parenchyma; c, palisade cells; 

 e, upper epidermis. X 400. 



Fig. 6. Lower epidermis of leaf: a, guard cell; b, epidermal cell be- 

 neath guard cell whose contents took a deep stain with methylene blue. 

 X 400. 



Fig. 7. Surface view of a bleached leaf embracing the epidermal, the 

 palisade, and the vascular bundle systems. X 183. 



