ver repairs its
leaves. It may put forth new leaves, but it never essays to patch up the
old ones. Every tree has such a superabundance of leaves that a few more
or less or a few torn and bruised ones do not seem to matter. When the
leaf surface is seriously curtailed, as it often is by some insect pest,
or some form of leaf-blight, or by the ravages of a hail-storm, the
growth of the tree and the maturing of its fruit is seriously checked.
To denude a tree of its foliage three years in succession usually
proves fatal. The vitality of the tree declines year by year till death
ensues.

To me nothing else about a tree is so remarkable as the extreme delicacy
of the mechanism by which it grows and lives, the fine hairlike rootlets
at the bottom and the microscopical cells of the leaves at the top. The
rootlets absorb the water charged with mineral salts from the soil, and
the leaves absorb the sunbeams from the air. So it looks as if the tree
were almost made of matter and spirit, like man; the ether with its
vibrations, on the one hand, and the earth with its inorganic compounds,
on the other--earth salts and sunlight. The sturdy oak, the gigantic
sequoia, are each equally finely organized in these parts that take hold
upon nature. We call certain plants gross feeders, and in a sense they
are; but all are delicate feeders in their mechanism of absorption from
the earth and air.

The tree touches the inorganic world at the two finest points of its
structure--the rootlets and the leaves. These attack the great crude
world of inorganic matter with weapons so fine that only the microscope
can fully reveal them to us. The animal world seizes its food in masses
little and big, and often gorges itself with it, but the vegetable,
through the agency of the solvent power of water, absorbs its
nourishment molecule by molecule.

A tree does not live by its big roots--these are mainly for strength
and to hold it to the ground. How they grip the rocks, fitting
themselves to them, as Lowell says, like molten metal! The tree's life
is in the fine hairlike rootlets that spring from the roots. Darwin says
those rootlets behave as if they had minute brains in their extremities.
They feel their way into the soil; they know the elements the plant
wants; some select more lime, others more potash, others more magnesia.
The wheat rootlets select more silica to make the stalk; the pea
rootlets select more lime: the pea does not need the silica