Page:Mrs Beeton's Book of Household Management.djvu/476

 CHAPTER XIV

The Empire of Nature has been, by general assent, divided into three great divisions or kingdoms: the first consisting of minerals, the second of vegetables, and the third of animals. The Mineral Kingdom comprises all inorganic objects devoid of life, but having a definite chemical composition, consisting of either a single element, as silver, or of two or three of these elements combined, as sodium chloride or common salt. When not mixed with any other substances, minerals are composed of similar particles, and if they possess a definite shape, are characterized by the geometric form their crystals assume, although all minerals are not distinctly crystalline. Minerals enter into the composition of the rocks, which constitute the solid portion of our globe, and guard the land against the encroachments of the sea.

The Vegetable Kingdom covers and beautifies the earth with an endless variety of form and colour. It consists, with some exceptions, of organic bodies which grow by the assimilation of inorganic substances, as water, carbonic acid, and ammonia, forming out of these organic complex substances, as sugar, starch, cellulose, etc. In the process of digestion plants break up carbonic acid into its two elements of oxygen and carbon, setting free the former which is required for the sustenance of animal life, and retaining the carbon necessary for vegetable life. The higher orders of plants are chiefly nourished by means of roots, breathe by the medium of leaves, and are propagated by seeds.

The Animal Kingdom in its lower types is closely allied to the Vegetable Kingdom, both of these constituting the organic series of natural objects. The bodies of each are composed of protoplasm, the basis of all life, a substance formed of carbon, hydrogen, nitrogen and oxygen. The nature and method of assimilating their food is the only means by which the distinction between plants and animals in their lowest forms can be clearly determined: the former subsisting on inorganic, and the latter on organic, matter.

In the case of the higher animals and plants, it is easy to assign any individual to its proper place in Nature, but it is almost impossible 414