Rubber is not rare
in nature, for it is contained in almost every milky juice. Every
country boy knows that he can get a self-feeding mucilage brush by
cutting off a milkweed stalk. The only native source so far utilized is
the guayule, which grows wild on the deserts of the Mexican and the
American border. The plant was discovered in 1852 by Dr. J.M. Bigelow
near Escondido Creek, Texas. Professor Asa Gray described it and named
it Parthenium argentatum, or the silver Pallas. When chopped up and
macerated guayule gives a satisfactory quality of caoutchouc in
profitable amounts. In 1911 seven thousand tons of guayule were
imported from Mexico; in 1917 only seventeen hundred tons. Why this
falling off? Because the eager exploiters had killed the goose that laid
the golden egg, or in plain language, pulled up the plant by the roots.
Now guayule is being cultivated and is reaped instead of being uprooted.
Experiments at the Tucson laboratory have recently removed the
difficulty of getting the seed to germinate under cultivation.
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