Page:The Oak.djvu/105

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THE SEEDLING AND YOUNG PLANT.

vades the universe—penetrate into the system. By means of the energy thus derived from the sun, the molecules of carbon dioxide and water are broken up in the meshes of this chlorophyll corpuscle, and experiments prove that the chlorophyll substance plays the part of the "trap to catch a sunbeam." We are not concerned with the hypothetical explanations offered for all the details of this remarkable process, but the present position of science enables us to say that, be these what they may, the chlorophyll corpuscle gains energy from the sun, and brings this energy to bear on the carbon dioxide and water in such a way that it does work in tearing asunder their molecules in the substance of the corpuscle. Then a curious series of results follow. The carbon, oxygen, and hydrogen undergo new re-arrangements, which amount finally to this—the substance known as starch, and consisting of carbon, hydrogen, and oxygen, is built up in the form of granules in the chlorophyll corpuscle, and the surplus oxygen escapes into the sap and finds its way to the intercellular passages, and thence through the stomata into the atmosphere.

It will be obvious from the foregoing that the granules of starch represent so much matter (especially carbon) obtained from the atmosphere outside the plant, and so much energy obtained from the sun; each granule may therefore be regarded as a packet of stored energy and matter won from the external universe.

The limits of this little book will not allow of my