e watched one squirrel stow cones under trash and in holes in the
thick beds of needles. These cones were buried near a tree, in a
dead limb of which the squirrel had a hole and a home. Harriet asked
many questions concerning the cones,--why they were buried, how the
squirrel found them when they were buried in the snow, and what became
of those which were left buried. I told her that during the winter the
squirrel came down and dug through the snow to the cones and then fed
upon the nuts. I also told her that squirrels usually buried more
cones than were eaten. The uneaten cones, being left in the ground,
were in a way planted, and the nuts in them in time sprouted, and
young trees came peeping up among the fallen leaves. The squirrel's
way of observing Arbor Day makes him a useful forester. Harriet said
she would tell all her boy and girl friends what she knew of this
squirrel's tree-planting ways, and would ask her uncle not to shoot
the little tree-planter.

As we followed the trail up through the woods, I told Harriet many
things concerning the trees, and the forces which influenced their
distribution and growth. While we were traveling westward in the
bottom of a gulch, I pointed out to her that the trees on the mountain
that rose on the right and sloped toward the south were of a different
kind from those on the mountain-side which rose on our left and sloped
toward the north. After traveling four miles and climbing up two
thousand feet above our starting-place, and, after from time to time
coming to and passing kinds of trees which did not grow lower down the
slopes, we at last came to timber-line, above which trees did not grow
at all.

In North America between timber-line on the Rockies, at an altitude of
about eleven thousand feet, and sea-level on the Florida coast, there
are about six hundred and twenty kinds of trees and shrubs growing.
Each kind usually grows in the soil and clime that is best suited to
its requirements; in other words, most trees are growing where they
can do the best, or where they can do better than any other kind. Some
trees do the best at the moist seashore; some thrive in swamps; others
live only on the desert's edge; some live on the edge of a river; and
still others manage to endure the storms of bleak heights.

At timber-line the trees have a hard time of it. All of them at this
place are dwarfed, many distorted, some crushed to the earth,
flattened out upon the ground like pr