Extent of life on the globe as proved by the microscope—Theory of Cuvier as to the nutrition of plants and animals—Vast extent of the microscopic living world—The “blooming of plants”—Results of disturbing the muddy banks of rivers—Sources of the bad odours of certain marshes and rivers—Remarkable influence of a change in temperature over the products of fermentation—Parasite theory of putrefaction, fermentation, and disease, refuted by Liebig, pp. [44]–54
CHAPTER VII.
Decomposition and metamorphosis of animal beings—Influence they exercise over the soil as a habitation for man—Disposal of the excreta and remains of animals and vegetables—Danger of these when accumulated—Immunity of savage tribes—Scurvy amongst the white troops at the Cape of Good Hope, the healthiest climate in the world—Metamorphoses of organic remains—Influence of oxygen, of nitrogen, and ammonia—Source of the inorganic principles—Fluate of lime in fossil bones—Danger to man of putrescent sea-water—Man’s incessant struggle with nature—Fatality of the climate of Rio pp. [55]–65
CHAPTER VIII.
Earth, air, and water, in relation to man—How modified by him—Results of that modification—Action and reaction—Antagonism of man to nature—Effects of human labour on the soil—How man protects his dwelling—Distinction between a drain and a sewer, a distinction first practically denied in England—Chemical elements of animal bodies—Nourishment of plants—Exhaustion of the soil in Virginia—Value of farm-yard manure—Agriculture in China—Effects of clearing the primæval forests of America—Causes of the hay-fever, typhus and typhoid fevers—Effects of bad ventilation—Importance of the infusoria in nature’s great scheme—Origin and action of humus—Functions of the humus and of the leaves—Means adopted in Holland for the conversion of a bog or morass into a polder—Antediluvian vegetation—Elements which require being restored to the soil—Belgian agriculturists—Statistics of Quetelet pp. [66]–88
CHAPTER IX.
On poisons, miasms, and contagions—Difficulties besetting the questions as to their essential nature and origin—Poison of typhus, of yellow fever, and of the remittent fevers of hot countries—Their appearance at uncertain and distant periods in an aggravated form—Statistics of the recurrence of remittents in the West Indies—Light thrown by chemistry on the subject—Fermentation and putrefaction—Peculiar poisons—Distinction between a miasm and a contagion—Odour perceptible in sick chambers—Ozone, pp. [89]–98
CHAPTER X.
On the servitude of rivers—Practical knowledge of the ancients—Early Roman history a fable—The great social problems of race and climate in some measure unknown to the Romans—First mooted in the reign of Justinian—Present phases of human society—How affected by these two problems—Influence of civilization over the earth pp. [99]–110