THE STUDY OF LEAVES. 219 



of mosaics ; that is, of dispositions of the leaves upon 

 branches so that they do not intercept the light from each 

 other, and an arrangement of the branches so that there 

 are " gaps " as it were permitting light to reach the leaves 

 on a lower level. The general shape of a tree also fits in 

 with this plan. The teacher should give some attention 



Fig. 87. Arrangement of Veins in the Leaf of the Pear. 



The Principal Veins only are shown on the right side, and the smallest 



Veinlets at C. 



to this point out of doors, cultivating an eye for seeing 

 mosaics which are apt to pass unnoticed otherwise. In 

 general it may be pointed out that, while the arrangement 

 of leaves of a particular tree is such that they must not 

 interfere with each other, they actually do so with those of 

 other individuals. This is a phase of the struggle for 



