Provision for Winter. 129 



lops roots. But the welfare of the tree demands that 

 there should be this polarity, and here we find it ; a 

 portion constantly plunging into the earth to keep 

 the plant in position, and furnish it with those salts 

 from the earth needed for its growth, and the opposite 

 portion just as plainly seeking the sunlight and the 

 air, having a structure just fitted for its work. The 

 root divides and subdivides, stretching far through 

 the soil, gathering in its richness ; while the leaves 

 give increased surface for sweeping the gases from 

 the air, and for preparing the crude materials for the 

 use of the plant. 



All the varied forms of leaves are such as to favor 

 radiation, and thus to condense the dews upon 

 them. The delicate but firm woody framework, 

 like the vessel's spars, keeps the soft tissues stretched 

 in place, that abundant surface may be secured with 

 light weight. 



\Ve cannot but admire that provision by which 

 all wide-leaved trees in the northern zone, where 

 snows and ice abound, are prepared for the winter. 

 Their leaves appear as by magic in the spring, 

 but the stem of every leaf has its curious joint, so 

 that when the summer is past and the leaf becomes 

 ripe or is killed by the frost, it drops from the tree, 

 and naked branches alone are exposed to the snow, 

 and ice, and winds of winter. Further south, wide- 

 leaved trees are evergreen ; but were they so in 

 northern climes, with their present structure, the 

 species would be destroyed. One single winter 

 would ruin our elms, and maples, and kindred trees; 



6* 



