» t 



Fig. 13. 



oopoooooooc 



Section of the leaf of a Cycad, being one of the most ancient styles 

 of leaf of which the structure is known, a, upper epidermis; d, upper 

 layer of cells, with grains of chlorophyll ; c, lower layer of cells, with 

 chlorophyll ; </, lower epidermis ; e, stomata, or breathing-pores, with 

 contractile cells for opening and closing. 



187 



■■-['X. 



