“Liquid manure being the richest part of the whole pile, care should be taken not to let escape what the bedding does not absorb. It should be first diluted with water and then applied to the growing crops. When it is desired for use in non-liquid form, it should be mixed with enough earth to absorb it, and the result is an excellent fertilizer. “In summer it is not unusual to enclose with hurdles a piece of land soon to be cultivated, and into this enclosure a flock of sheep is driven to pass the night under the care of the shepherd in his movable hut, and with the protection of trusty dogs well able to cope with any marauding wolves. The next night the flock is quartered in another spot, and so on until the entire field has thus served, a little at a time, as stable for the flock. The purpose of this procedure is to utilize the excrement, both solid and liquid, left behind by the flock. In one night a sheep can fertilize a square meter of surface. This method of fertilizing is very effective because of the complete absorption of the fluid matter by the soil. “Off the coast of Peru in South America are several small islands which form a common rendezvous for great numbers of sea-birds. Birds that frequent the sea are all notorious for their insatiable appetite. Constantly in search of fish, which they live on, they spend the day exploring the surface of the waters at immense distance from land. Nature has endowed them with prodigious flying power. To these indefatigable rovers an aërial promenade of some hundreds of leagues before dinner is a mere nothing. Scattered during the day in all directions in quest of prey, they reach the islets in the evening to spend the night, arriving in flocks so dense as to darken the sky. Being well fed, thanks to their foraging excursions, they cover the ground at night with a thick layer of excrement. And as this has been going on century after century ever since the world was made, these deposits, piled one on another, have at last become massive beds twenty or thirty meters thick, and so hard, so compact, that to break them it is necessary to use a pick or a petard, just as one would in quarrying stone. Workmen operate this dung mine, and vessels from all parts of the world fetch cargoes of this valuable material, which is called guano. This enormous mass of dung, which has by the lapse of ages been turned into a sort of whitish loam, gives Peru an annual revenue amounting to sixty millions of francs. “Guano is the strongest fertilizer known to agriculture. It is scattered broadcast over the field when vegetation is starting, and for the best results a rather damp time is chosen for this work in order that the moisture may convey to the roots of the plants, by gradual infiltration, the soluble constituents of the fertilizer. The action of guano on vegetation is of the promptest, most powerful sort.” CHAPTER XIV THE STALK OF THE PLANT