Page:Popular Science Monthly Volume 25.djvu/62

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54
THE POPULAR SCIENCE MONTHLY.

knob is in fact the embryo palm or seedling, for whose ultimate benefit the whole arrangement (in brown and green) has been invented. That is very much the way with man: he notices what concerns his own appetite, and omits all the really important parts of the whole subject. We think the use of the hole is to let out the milk; but the nut knows that its real object is to let out the seedling. The knob grows out at last into the young plantlet, and it is by means of the soft hole that it makes its escape through the shell to the air and the sunshine which it seeks without.

This brings us really down at last to the true raison d’être for the milk in the cocoa-nut. As the seed or kernel can not easily get at much water from outside, it has a good supply of water laid up for it ready beforehand within its own encircling shell. The mother-liquid from which the pulp or nutty part has been deposited remains in the center, as the milk, till the tiny embryo begins to sprout. As soon as it does so, the little knob which was at first so very small enlarges rapidly and absorbs the water, till it grows out into a big, spongy cellular mass, which at last almost fills up the entire shell. At the same time, its other end pushes its way out through the soft hole, and then gives birth to a growing bud at the top—the future stem and leaves—and to a number of long threads beneath—the future roots. Meanwhile, the spongy mass inside begins gradually to absorb all the nutty part, using up its oils and starches for the purpose of feeding the young plant above, until it is of an age to expand its leaves to the open tropical sunlight and shift for itself in the struggle for life. It seems at first sight very hard to understand how any tissue so solid as the pulp of cocoa-nut can be thus softened and absorbed without any visible cause; but in the subtile chemistry of living vegetation such a transformation is comparatively simple and easy to perform. Nature sometimes works much greater miracles than this in the same way: for example, what is called vegetable ivory, a substance so solid that it can be carved or turned only with great difficulty, is really the kernel of another palm-nut, allied to the cocoa-palm, and its very stony particles are all similarly absorbed during germination by the dissolving power of the young seedling.

Why, however, has the cocoa-nut three pores at the top instead of one, and why are two out of the three so carefully and firmly sealed up? The explanation of this strange peculiarity is only to be found in the ancestral history of the cocoa-nut kind. Most nuts, indeed, start in their earlier stage as if they meant to produce two or more seeds each; but, as they ripen, all the seeds except one become abortive. The almond, for example, has in the flower two seeds or kernels to each nut; but in the ripe state there is generally only one, though occasionally we find an almond with two—a philopena, as we commonly call it—just to keep in memory the original arrangement of its earlier ancestors. The reason for this is that plants whose fruits