140 



THE BEAUTIES OF NATURE 



the general plane of the branch, which bends 

 slightly at each internode. The basal half of 

 the leaf fits the swell of 

 the twig, while the upper 

 half follows the edge of 

 the leaf above ; and the 

 form of the inner edge 

 being thus determined, 

 decides that of the outer 

 one also. 



The weight, and con- 

 sequently the size of the 

 leaf, is limited by the 

 strength of the twig ; and, 

 again, in a climate such as 

 ours it is important to plants to have their 

 leaves so arranged as to secure the maximum 

 of light. Hence in leaves which lie parallel to 

 the plane of the boughs, as in the Beech, the 

 width depends partly on the distance between 

 the buds; if the leaves were broader, they 

 would overlap, if they were narrower, space 

 would be wasted. Consequently the width 

 being determined by the distance between the 

 buds, and the size depending on the weight 



Fig. 15. — Beech. 



