TREE-FOOD. 263 



in the plentiful rain of the Winter season, or in 

 the thawing of rime and snow. Then begins a 

 rapid process of decay, and the resolution of the 

 dry organic constituents of the leaves into liquid, 

 by the dilution of rain. Slowly but surely the 

 process goes on- leaves are turned into leaf- 

 mould, and the liquified leaf-mould enriches, all 

 around the roots, the earth which had, in the 

 previous season, been drained of its resources, to 

 supply the urgent and pressing wants of the 

 growing tree. 



The rains of Winter, too, as well as those 

 of spring and summer, and the melted snow, 

 carry into the earth the gases which they had, 

 in their descent to the ground, absorbed from the 

 air, and thus they assist in the process of en- 

 richment. The store of food goes on accumu- 

 lating. The lowest portion of the surface-soil, 

 where the leaf-mould is perfectly formed, enters 

 at once, by the action of rain, into the soil below ; 

 the stratum of leaves, next above, is only half- 

 decayed ; and the surface-bed consists of those 

 last fallen, awaiting their turn for decay and final 

 incorporation into the forest soil. 



