86 OUR WOODLAND TREES. 
formed, and sent out to seek the greater and 
greater supplies of moisture, impregnated with che- 
mical substances, required by increasing growth. 
Meanwhile, succeeding spring and summer have 
increased the breathing power of the Tree by 
multiplication of the number of its leaves, and 
consequent augmentation of the green surfaces on 
which the sun exercises its beneficent and won- 
derful power. By a wise provision of Nature, the 
exhaustion of the soil—by the rootlets—of the 
elements which have ministered to the life and 
growth of the Tree has been anticipated: for the 
fall of the leaves each year has brought decay to 
their tender and delicate framework, which has 
thus provided the surface soil with the very mate- 
rials which have been carried up from beneath, 
and transmuted into the beautiful tracery of the 
foliage ; and in due time, when the subtle opera- 
tion of Nature called decomposition has been fully 
effected, the elemental substances of the leaves 
have, by the gentle influence of rain, been carried 
down once more into the earth. 
Thus it is that, by the combination of these 
varied and beautiful forces of Nature, exercised 
