The Rubber Tree
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.