Page:Popular Science Monthly Volume 20.djvu/842

820 ornamental flowers than any other family of plants in the whole world. Among a widely-different group we get other herbs which lay by rich stores of starch, or similar nutritious substances, in thickened under-ground branches, known as tubers; such, for example, are the potato and the Jerusalem artichoke. Sometimes the root itself is the store-house for the accumulated food-stuffs, as in the dahlia, the carrot, the radish, and the turnip. In all these cases, the plant obviously derives benefit from the habit which it has acquired of hiding away its reserve fund beneath the ground, where it is much less likely to be discovered and eaten by its animal foes. For it is obvious that these special reservoirs of energetic material, which the plant intends as food for its own flower or for its future offspring, are exactly those parts which animals will be likely unfairly to appropriate to their personal use. What feeds a plant will feed a squirrel, a mouse, a pig, or a man, just as well. Each requires just the same free elements, whose combination with oxygen may yield it heat and movement. Thus it happens that the parts of plants which we human beings mainly use as food-stuffs are just the organs where starch has been laid by for the plant's own domestic economy—seeds, as in the pea, bean, wheat, maize, barley, rice, or millet; tubers, as in the potato and Jerusalem artichoke; corns, as in the yam or tare; and roots, as in arrow-root, turnip, parsnip and carrot. In all these, and in many other cases, the habit first set up by Nature has been sedulously encouraged and increased by man's deliberate selection. What man thus consciously effects in a few generations, the survival of the fittest has unconsciously effected through many long previous ages of native development.—Knowledge.

 

HE Egyptians, Greeks, and Romans regulated their most important field-labors, the sowing and gathering of their crops, etc., by their observations of the movements of the heavenly bodies, as the rising and setting of the stars. It is obvious that this system gives only an approximation to the true time; for not only the time of the rising and setting of the stars, but also the relative situation of the stars to each other, is changed by the precession of the equinoxes. Notwithstanding this, this system is still used by some of the less civilized peoples of the East Indies; and, although the Dutch Government employs the Gregorian calendar exclusively in its colonies, the 