CHAPTER IV. ENERGY. Energy of motion and of position—Energy can be transformed, not created or destroyed—Not created by free-will—Conservation of mechanical power—Convertibility of heat and work—Nature of heat—The steam-engine—Different forms of energy—Gravity—Molecular energy—Chemical energy—Dynamite—Chemical affinities—Electricity—Produced by friction—By the voltaic battery—Electric currents—Arc light—Induction—Magnetism—The magnetic needle—The electric telegraph—The telephone—Dynamo-electric engine—Accumulator 36 CHAPTER V. POLARITY IN MATTER. Ultimate elements of universe—Built up by polarity—Experiment with magnet—Chemical affinity—Atomic poles—Alkalies and acids—Quantivalence—Atomicity—Isomerism—Chemical stability—Thermochemistry—Definition of atoms—All matter built up by polar forces 65 CHAPTER VI. POLARITY IN LIFE. Contrast of living and dead—Eating and being eaten—Trace matter upwards and life downwards—Colloids—Cells—Protoplasm—Monera—Composition of protoplasm—Essential qualities of life—Nutrition and sensation—Motion—Reproduction—Spontaneous generation—Organic compounds—Polar conditions of life 76 CHAPTER VII. PRIMITIVE POLARITIES—PLANT AND ANIMAL. Contrast in developed life—Plants producers, animals consumers—Differences disappear in simple forms—Zoophytes— Protista—Nummulites—Corals—Fungi—Lichens—Insectivorous plants—Geological succession—Primary period, Algæ and Ferns—Secondary period, Gymnosperms—Tertiary and recent, Angiosperms—Monocotyledons and Dicotyledons—Parallel evolution of animal life—Primary, protista, mollusca, and fish—Secondary, reptiles—Tertiary and recent, mammals 92 CHAPTER VIII. PRIMITIVE POLARITIES—POLARITY OF SEX. Sexual generation—Base of ancient cosmogonies—Propagation non-sexual in simpler forms—Amœba and cells—Germs and buds—Anemones—Worms—Spores—Origin of sex—Ovary and male organ—Hermaphrodites—Parthenogenesis—Bees and insects—Man and woman—Characters of each sex—Woman’s position—Improved by civilisation—Christianity the feminine pole—Monogamy the law of nature—Tone respecting women test of character—Women in literature—In society—Attraction and repulsion of sexes—Like attracts unlike—Ideal marriage—Woman’s rights and modern legislation 102 CHAPTER IX. PRIMITIVE POLARITIES—HEREDITY AND VARIATION.