CHAP, in.] PROTECTIVE ARRANGEMENTS. 



101 



plant or to be stored up for future use. Although the 

 points already enumerated show the higher development 

 of the dicotyledonous over the monocotyledonous leaf, 

 yet undoubtedly the greatest advance made by the leaves 

 of the group under consideration is that connected with 



Fig. 28. Leaf of melon, a typical Dicotyledon, showing stalk or 

 petiole, prominent anastomosing veins forming a network and pro- 

 jecting from the under surface, also the cut edge or margin. 



protection against both climate and living enemies. 

 The former only will be considered at present. In 

 Monocotyledons, the leaf, when once fully expanded, 

 remains rigid and motionless, its working surface being 

 constantly exposed to the chills of the night air and to 

 the dust settling down and covering up its chlorophyll 



