THE LEAF iii 



After this exposition we shall not be surprised to find that 

 nature has arranged these chief formative organs in such a 



0,0 



Pio. 15.— Sdbeaoe View ahd Skciion op the Leaf op the Baklby. 

 ^, a piece covered by the epidermis ; F^ portion from which the epidermis has been 

 stripped ; 0, long, thin-walled epidermis cells covering the mesophyll, which lies be- 

 tween two veins of the leaf ; 00^ thick-walled epidermis cells covering in^the vascular 

 bundles (g) ; «p, stomata leading to the spongy parenchyma, with large intercellular 

 spaces (i) ; ra, mesophyE cells ; il, short hair on margin of leaf ; f, prosenchymatous 

 strand of cells strengthening the leaf margin. 



way as to derive the greatest possible benefit from the smallest 

 amount of substance. This is done by building the assimi- 



