I have editors and printers, who daily send me an account of what is going on throughout the world, among all these people who serve me; and in a corner of my house I have books, the miracle of all my possessions, more wonderful than the wishing-cap of the Arabian tales; for they transport me instantly, not only to all places, but to all times. LABOUR is life :-'tis the still water faileth; ARNOTT. Flowers droop and die in the stillness of noon. Play the sweet keys wouldst thou keep them in tune. Work at thy task, be it ever so lowly,- LONGFELLOW. THE THREE KINGDOMS OF NATURE. NATURAL objects may be conveniently classed under the three grand divisions of Minerals, Vegetables, and Animals. This classification, indeed, is open to the objection of not being wholly exhaustive, inasmuch as there are some things, such as water and air, which are not comprehended under it. Yet it is sufficiently accurate for the purposes of popular science; and if we agree to call water a mineral, it is also tolerably complete. I. MINERALS.-Under the head of minerals are included all inorganic bodies-that is, all bodies destitute of organization and life, such as sand, clay, metals, etc. Minerals are usually found in a solid state, but not always. Thus, quicksilver is fluid, except when exposed to intense cold; lead does not cease to be a mineral when it is melted; and water, if a mineral, is entitled to the name, alike when it exists in its ordinary liquid form, when it is frozen into ice, and when it passes into the gaseous form of vapour or steam. With the exception of the pure metals—gold, silver, copper, etc.-very few of the minerals are simple, uncompounded substances. Most of them are bodies made up of several ingredients; and while in some these ingredients are always the same and combined in the same proportion, in others they vary both in kind and in degree. Thus, limestone is always made up of lime and carbonic acid combined in fixed proportions; whereas sandstone is composed of grains of all sorts of substances mingled together without any regard to quality or proportion. The minerals which are composed of definite ingredients are distinguished by a very remarkable property. On passing from a fluid to a solid state, they always assume the form of what is called crys tals; a word which is used in science to denote, not transparency, but regularity of shape. A few, indeed, become transparent; as, for instance, a piece of limestone, which loses its dull appearance and becomes clear like glass. But most of them retain their opacity, and acquire only a crystalline form. Nor is it only after a process of artificial fusion that minerals thus crystallize; many of them occur in their natural state as crystals. Crystals of carbonate of lime, for example, are found in great abundance in the veins of many limestone rocks; and some limestones consist almost entirely of an assemblage of interlaced crystals. The whole crust of the earth is composed of minerals, which generally lie one above another in beds or strata of various thickness. These beds are in some places nearly horizontal; but in other instances, particularly in mountainous countries, they have a waving or bending form, their different degrees of inclination determining the external shape or contour of a district. II. VEGETABLES.-Vegetables or Plants are not mere inorganic substances like minerals, but possess the higher properties of organization and life. They are all, from the majestic tree to the microscopic fungus, living, organized bodies. Apart from other characteristics, there is enough to distinguish plants from minerals, in the mere fact that they grow. A mineral does not and cannot grow. If it increases in bulk, as in the case of a rolling snowball, or an accumulating heap of gravel, the increase is due, not to any action or movement from within, but to additions or accretions from without. A plant, on the other hand, increases in size by expansion from within-by self-development-by growth. A block of sandstone is only a collection of sandgrains heaped one upon another; an oak tree is an acorn developed by growth. A plant has two sets of organs; nutritive organs, as the root, the stem, the leaves, which collect and prepare the food that builds up the plant; and reproductive organs, as the flower, wherewith to produce and mature the seed. A few plants which have no flowers produce seeds, or rather germs, by means of other and peculiar organs. But all the more familiar plants bear flowers which produce the seed. The flowerless plants are chiefly the ferns, mosses, lichens, seaweeds, and mushrooms. The most important function performed by plants is that of preparing food for man and the other members of the animal kingdom. For this end they feed on mineral substances, and, by a wonderful process of assimilation, convert these into vegetable substances. Man and the lower animals cannot feed on inorganic matter. No mineral, with the single exception of salt, is fit food for animals. But mineral substances are the appropriate food of plants; and it is by taking up these substances into their own structure, and converting them into starch, sugar, and other vegetable products, that plants prepare suitable nutriment for the animal creation. Besides preparing food for animals, plants perform the almost equally important function of purifying the air. As animals in breathing constantly inhale oxygen and exhale foul air, the effect of animal respiration is necessarily to de teriorate the atmosphere by withdrawing the oxygen and replacing it by noxious gases; and were this process to be allowed to go on without check or counteraction, the atmosphere would erelong become as fatal to animal life as the Black Hole of Calcutta. Such a disastrous result is precluded by the agency of plants. They possess the property of absorbing the noxious gases and of giving out oxygen. They, therefore, withdraw from the atmosphere what animals impart to it, and supply to it what animals consume. And thus the gases which compose the air we breathe are constantly maintained in the proportion necessary to the support of life. Plants are the more serviceable to man, that they admit of being modified and improved by culture. By means of buds or slips, or a change of soil and climate, we may produce what is called a variety, that is, an individual plant differing in some respects from the species to which it be. longs; and in proof of the immense value to us of this property of plants, it will suffice to name the fact that our cereal crops, culinary vegetables, and orchard fruits are all varieties. These varieties, it is true, cannot be considered as a permanent addition to the vegetable kingdom, for when their seeds are sown in ordinary soil and left to grow wild, they rapidly degenerate and erelong return to the type of the original species. Yet, when carefully cultivated-as by the farmer in the case of the grains, and by the horticulturist in the case of the fruits-they may be continued for generations; and when old varieties fail, new ones, of equal value to man, may be produced and propagated. The number of individual plants is beyond all computation. Even the known species are upwards of 120,000; while there are, doubtless, many thousands more yet destined to reward the search of the botanist. They are universally diffused,―most abundant, indeed, in tropical regions, and more sparse as we approach towards the poles, but nowhere absent. And, what specially argues the goodness of the Great Maker, they are invariably distributed in fine adaptation to the exigencies alike of climate and of animal life; every zone, nay, every district of every zone, yielding the tree, the shrub, the herbaceous plant, best adapted to its atmospheric and animal necessities. III. ANIMALS.-Besides organization and life, Animals possess voluntary motion and sensation. Plants are stationary; animals have the power of free movement. Plants have no sense of their own beauty or fragrance; animals have the capacity of perceiving and feeling. And in the case of man, the head of the animal kingdom, there are the yet higher powers of reason and conscience. Animal life being of a higher order than vegetable life, it is natural to expect a more complicated organization in animals than in plants. Nor is this greater elaborateness of structure apparent only in those organs which are peculiar to animals the organs of motion and sensation; it is equally apparent in the nutritive and reproductive organs. In proof of this, we need only look at the organs by which animals procure their food. These organs are of every form of construction, comprising prehensile machines, pumps, syphons, saws, projectiles. The talons of the eagle, the claws of the tiger, the proboscis of the elephant, are examples of organs of prehension. The double tube of the butterfly which takes up liquid nutriment, and the lancet of the gnat which at once pierces the skin of its prey and forms a tube for suction, are examples of pumps and suckers. Even in the creatures of low organization which inhabit the sea, the organs for procuring food display an exquisite mechanism. Many of the humble molluscs are furnished with a tongue that can rasp the sea-weed so as to reduce it to a pulp. The starfish has hundreds of tubular suckers with which to seize any unfortunate periwinkle that may come in its way. The sea-jellies have long contractile filaments by which to sting and grasp their victims. And one little fish (Choetodon rostratus) has a projectile apparatus which enables it to shoot with a drop of water the small flies on which it lives. That, however, which chiefly raises animals above plants in the scale of being, is the system of organs which we call the Nerves and Brain. For with the nervous system are connected in some mysterious way which we cannot explain, not |