LIST OF BOOKS. The following books will assist the teacher and student in farther prosecuting the various subjects here treated of: Francis' British Botanist; and Botanical Terms (Elementary). Withering's British Flora. Loudon's Encyclopedia of Plants. Knight's Library-Vegetable Substances Used as the Food of The Menageries. - Pictorial Museum, 4to, containing Numerous Figures of Animals. Paterson's Introduction to Zoology for Schools. Carpenter's Physiology. Johnston's British Zoophytes. Introduction to Conchology. British Zoology. By Jones, Bell, E. Forbes, Yarrel, &c. Hamilton Smith's do. Latham's Varieties of Man. The Botanical and Zoological Parts of Johnston's Physical Atlas. As many good drawings and specimens of animals and plants should be exhibited to pupils as possible; and every opportunity should be taken of calling attention to living objects of nature. A collection of minerals, plants, birds and other animals, should have a place in every liberal establishment for the tuition of youth. PHYSICAL GEOGRAPHY. ORGANIC LIFE. SECTION 1.-FORM AND COMPOSITION OF ORGANIC BODIES. THERE are two distinct states in which bodies exist on the earth, inorganic and organic. Rocks, minerals, water, and air, are inorganic matters. Plants and animals are called organised bodies, because they have a structure made up of cells, tubes, and membranes, with distinct organs, as root, leaves, heart, stomach. If you take a mineral substance, a piece of rock or crystal, and break it into minute parts, each part is complete in itself, and is the same in every respect but size with the body from which it was broken; but if you divide an organised being thus, every part differs from the other, as the root, stem, leaf of a plant; or the head, arms, heart, stomach of an animal. Inorganic bodies are governed by mechanical and chemical laws. Illustrated by a stone falling to the earth by gravity, the attraction of a needle to the magnet, the expansion of air by heat, and the solution of salt in water. Organic bodies are endowed with vital powers, which are superior to, in so far as they control, the mechanical and chemical laws of matter. A Thus a plant or animal lives and grows by its vital powers. When these cease, it is said to die, and then its substance is acted upon by chemical and mechanical agencies, and it moulders into earthy inorganic matter. A plant shoots its stem upwards, contrary to the laws of gravity, and animals stand and move by their own muscular powers. The vital powers resist putrefaction. The bodies of plants and animals are formed out of a few earthy substances, water, and air. These simple substances enter into the composition of organic beings in the following order of predominance:-Carbon, oxygen, hydrogen, nitrogen, potassium, calcium, phosphorus, silicon, sulphur, sodium, magnesium, chlorine, iron, fluorine, aluminum, bromine, iodine. The vital actions of plants and animals, however, in conjunction with chemical processes, produce new combinations of these elements. Plants produce sugar, starch, gum, gluten, albumen, caseine, oil, woody fibre. Animals produce flesh, which consists of albumen and gluten, and gelatine or jelly, fat, serum. Wheat-flour yields starch and gluten; the sugar-cane and mapletree, sugar; the fir-tree, oil of turpentine; the cinnamon-tree, oil of cinnamon. Lint-seed and rape-seed, common oil. The skins, hoofs, and horns of animals yield gelatine or glue; the muscles or fleshy parts, gluten and albumen. The white of eggs is nearly a pure albumen. Sulphur imparts a flavour to mustard, cresses, and other herbs. Phosphorus abounds in fish and shell-fish. Iron gives the red colour to blood. Silex or flint forms the outer crust of the bamboo cane, and of wheat and oat stalks; calcium or lime, the hard parts of bones and shells. Potash is found in the ashes of burnt land-plants; soda in kelp, the ashes of sea-weeds. The simplest structure of a plant or animal is that of a series of minute cells, communicating with each other, and forming a net-work through which circulates a fluid. In this fluid are seen minute globules of a round or oval shape, with a dark spot or nucleus in the centre. |