Electrolysis-Indestructibility of Force-Various Modes dis- covered of Decomposing Substances-John Dalton, chemist— Law of Definite Proportions-Law of Multiple Proportions- SCIENCE OF THE NINETEENTH CENTURY (CONTINUED). The Organic Sciences are too difficult to follow out in detail— Jussieu's Natural System of Plants-Goethe proves the Meta- morphosis of Plants—Humboldt studies the Lines of Average 1858 . 380 SCIENCE OF THE NINETEENTH CENTURY (CONTINUED). The three Naturalists, Lamarck, Cuvier, and Geoffroy St.-Hilaire -Cuvier begins the Museum of Comparative Anatomy-La- marck's History of Invertebrate Animals-G. St.-Hilaire brings Natural History Collections from Egypt-Lamarck on the Development of Animals-G. St.-Hilaire on Homology,' or the similarity in the parts of different animals-Cuvier's 'Règne Animal' and his Classification of Animals-Cuvier on the Per- fect Agreement between the Different Parts of an animal-He Studies and Restores the Remains of Fossil Animals-His 'Ossemens Fossiles '-Death of Cuvier-Von Baer on the Study of Embryology-His History of the Development of Animals, 1828 388 'Principles of Geology' published in 1830-Louis Agassiz: his early life-De Saussure's Study of Glaciers-Agassiz on Europe and North America being once covered with Ice-Boucher de Perthes on Ancient Flint Implements-McEnery on Flint Im- SCIENCE OF THE NINETEENTH CENTURY (CONTINUED). Facts which led Naturalists to believe that the different kinds of Animals are descended from Common Ancestors-All Animals of each class formed on one Plan-Embryological Structure- Living and Fossil Animals of a country resemble each other- Gradual Succession of Animals on the Globe-Links between different species-Darwin's Theory of Natural Selection- Wallace worked out the same Theory independently-Sketch of the Theory of Natural Selection-Selection of Animals by Man- Selection by Natural Causes-Difficulties in Natural History which are explained by this Theory-Foolish Prejudices against A SHORT HISTORY OF NATURAL SCIENCE. INTRODUCTION, AS THIS little work is to be a history of Natural Science, it will be as well to begin by trying to understand what Science is. The word itself comes from scio, I know, and means simply knowledge. The science of botany is therefore the knowledge of plants; and the science of astronomy, the knowledge of the heavenly bodies. But now comes the question, What kind of knowledge is required? You might be able to tell the names of all the plants in the world, and of all the stars in the sky, and yet have scarcely any real knowledge of botany or astronomy. You will easily understand this if we compare it with something you meet with in daily life. Suppose I took you into a large school and told you the names of all the children there ; even if you learnt these names by heart, you could not say you knew the children, or anything about them, beyond their names. One might be ill-tempered, another good-tempered; one might have a home and a father and 2 mother, another might be an orphan and homeless, and you would find their mere names of no use to you if you wished to choose one of them to do any work, or to be your friend and companion. For this you would want to learn their character, their habits, and other real facts about them. Now this last is just the kind of knowledge which is required in science. If, besides the name of a plant, you know its different parts, the shape of its leaves, the number of its seeds, and how they are arranged in the seed-vessel, the number of stamens or thread-like bodies in the middle of the flower, the number and colour of its petals or flowerleaves, and many other points like these, then you know something of structural botany. If you know, besides, how a plant takes up food, how it breathes, and how the sunlight acts upon the leaves and alters the juices of the plant, then you know something of the life of the plant, or physiological botany. If you know where the plant grows best, in what soil, in what climate, and in what countries, then you know something of geographical botany; and if your knowledge is accurate and carefully learnt it is real science. By this you will see that science means not merely knowledge, but an accurate and clear knowledge about the things which we see around us in the universe. In the present day, people are beginning to teach children much more on these subjects than they did forty years ago, and every intelligent boy or girl probably knows that Astronomy is the science of the sun, stars, and planets; Physics and Mechanics, the sciences which teach the properties of bodies and their laws of motion; Biology the science of life; Geology the science of the earth, teaching us how the different rocks have been formed; and Chemistry the science which treats of the materials of which all substances are made, and shows the |