And beyond the beaches where the beach peas dig so diligently are the seaweeds--with a talent for picking and choosing all their own. Dr. Julius Sachs, a leading German botanist, believes that the parts of plants owe their form, as crystals do, to their peculiarities of substance; that just as salt crystallizes in one shape and sugar in another, so a seaweed or a tulip is moulded by the character of its juices. Something certainly of the crystal's faculty for picking out particles akin to itself, and building with them, is shown by the kelp which attracts from the ocean both iodine and bromine--often dissolved though they are in a million times their bulk of sea water. This trait of choosing this or that dish from the feast afforded by sea or soil or air is not peculiar to the seaweeds; every plant displays it. Beech trees love to grow on limestone and thus declare to the explorer the limestone ridge he seeks. In the Horn silver mine, of Utah, the zinc mingled with the silver ore is betrayed by the abundance of the zinc violet, a delicate and beautiful cousin of the pansy. In Germany this little flower is admittedly a signal of zinc in the earth, and zinc is found in its juices. The late Mr. William Dorn, of South Carolina, had faith in a bush, of unrecorded name, as betokening gold-bearing veins beneath it. That his faith was not without foundation is proved by the large fortune he won as a gold miner in the Blue Ridge country--his guide the bush aforesaid. Mr. Rossiter W. Raymond, the eminent mining engineer of New York, has given some attention to this matter of "indicative plants." He is of the opinion that its unwritten lore among practical miners, prospectors, hunters, and Indians is well worth sifting. Their observations, often faulty, may occasionally be sound and valuable enough richly to repay the trouble of separating truth from error. When we see how important as signs of water many plants can be, why may we not find other plants denoting the minerals which they especially relish as food or condiment? Of more account than gold or silver are the harvests of wheat and corn that ripen in our fields. There the special appetites of plants have much more than merely curious interest for the farmer. He knows full well that his land is but a larder which serves him best when not part but all its stores are in demand. Hence his crop "rotation," his succession of wheat to clover, of grass to both. Were he to grow barley every year he would soon find his soil bared of all the food that barley asks, while fare for peas or clover stood scarcely broached. If he insists on planting barley always, then he must perforce restore to the land the food for barley constantly withdrawn. [Illustration: Maple Seed, with pair of wings]