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For
the very first of the rubber story we may thank a little
wood-boring beetle, and the way nature has of helping her
children to protect themselves.
The
thistle of the meadow is as safe from hungry cattle as
though fenced in by barbed wire. A cow must be starving that
would care to flavor her luncheon with the needles that the
thistle bears. The common skunk cabbage would make a
tempting meal for her after a winter of dry feeding, had not
Nature given it an odor that disgusts even a spring-time
appetite. The milkweed welcomes the bees and flies that help
to distribute her pollen where she wants it spread, but she
has her own way of punishing the useless thieves that
trespass up her stalk. Wherever the hooks of an insect's
feet pierce her tender skin, she pours out a milky juice to
entangle its feet and body, and it is a lucky bug that
succeeds in escaping before this juice hardens, and holds
him a prisoner condemned to die.
All
over the world there are plants with the same ability that
the milkweed has, but it is especially true of certain trees
and vines of the tropics. As soon as the little beetle
begins to bore into the bark of one of these trees, there
pours out a sticky, milky fluid that kills the insect at
once. If this were all, the wound would remain open, ready
for the next robber who came along. In order that the break
may be healed, a cement is necessary, but not a hard,
unyielding one, for that would crumble away with the motion
of the tree in the wind.
This
juice is not the sap of the rubber tree. Sap, which is the
life-blood of the tree, flows through the wood, but the
juice we are describing is contained in the inner bark, a
thin layer directly below the outer bark.
Scientific
men call this juice latex. It is like milk in three ways: it
is white, it contains tiny particles that rise to the top
like cream, and it spoils quickly.
The
Hevea tree grows sixty feet tall, and when full grown is
eight or ten feet around. It rises as straight as an elm,
with high branching limbs and long, smooth oval leaves.
Sprays of pale flowers blossom upon it in August, followed
in a few months by pods containing three speckled seeds
which look like smooth, slightly flattened nutmegs. When the
seeds are ready to drop the outer covering of the pod bursts
with a loud report, the seeds shooting in all directions.
This
is Nature's clever scheme to spread the Hevea family. The
tree grows wild in the hot, damp forests of the Amazon
valley and in other parts of South America that have a
similar climate. The ideal climate for the rubber tree is
one which is uniform all the year round, from eighty-nine to
ninety-four degrees at noon, and riot lower than seventy
degrees at night. The Amazon country has a rainy season
which lasts half the year, though the other season is by no
means a dry one, and so for half the time the jungles are
flooded.
These
rubber storehouses had been growing for thousands of years
in the Amazon jungle with their wealth securely sealed up in
their bark, the peck of a bird, the boring of a beetle, or
the scratch of a climbing animal being the only draft upon
their treasure. The trees around the mouth of the river
supplied whatever was needed for the little manufacturing
that was at first done. But the discovery that made a
universal use for rubber changed all this. Brazil was
surprised to find what great treasure her forests contained.
Large rubber areas were found a thousand miles up the river
and she began in a serious way to develop a large crude
rubber business.
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