ings. They're all the same age. Four
of them stand, say, ten feet or more high an' they're as large around as
my wrist. Here's one that's largest. See how full-foliaged he is--how he
stands over most of the others, but not so much over these four next to
him. They all stand close together, very close, you see. Most of them
are no larger than my thumb. Look how few branches they have, an' none
low down. Look at how few leaves. Do you see how all the branches stand
out toward the east an' south--how the leaves, of course, face the same
way? See how one branch of one tree bends aside one from another tree.
That's a fight for the sunlight. Here are one--two--three dead trees.
Look, I can snap them off. An' now look down under them. Here are little
trees five feet high--four feet high--down to these only a foot
high. Look how pale, delicate, fragile, unhealthy! They get so little
sunshine. They were born with the other trees, but did not get an equal
start. Position gives the advantage, perhaps."

Dale led the girls around the little grove, illustrating his words by
action. He seemed deeply in earnest.

"You understand it's a fight for water an' sun. But mostly sun, because,
if the leaves can absorb the sun, the tree an' roots will grow to grasp
the needed moisture. Shade is death--slow death to the life of trees.
These little aspens are fightin' for place in the sunlight. It is a
merciless battle. They push an' bend one another's branches aside an'
choke them. Only perhaps half of these aspens will survive, to make one
of the larger clumps, such as that one of full-grown trees over there.
One season will give advantage to this saplin' an' next year to that
one. A few seasons' advantage to one assures its dominance over the
others. But it is never sure of holdin' that dominance. An 'if wind or
storm or a strong-growin' rival does not overthrow it, then sooner or
later old age will. For there is absolute and continual fight. What is
true of these aspens is true of all the trees in the forest an' of all
plant life in the forest. What is most wonderful to me is the tenacity
of life."

And next day Dale showed them an even more striking example of this
mystery of nature.

He guided them on horseback up one of the thick, verdant-wooded slopes,
calling their attention at various times to the different growths, until
they emerged on the summit of the ridge where the timber grew scant
and dwarfed. At the edge of timber-line he s