The history of epidemics adverse to the theory of Macculloch--Results of confounding drains with sewers, and of converting drains into drain-sewers--Influence of the external world (earth, air, and water) over man, first examined by Hippocrates in his celebrated treatise, “_De aere, aquis et locis_,”[1] but with other views--Influence of modern chemistry over physiology--Men now expect from chemistry a solution of some of the great problems of physiology and pathology still unsolved pp. 6–14 [1] Περι αερον, ὑδατων καὶ τοπων. Cary’s edition. Paris. 1806. CHAPTER III. The great plague in the time of Justinian--View as to its African origin, and strictly contagious nature, adopted by Gibbon--Admits, however, the necessity for an insalubrious condition of the atmosphere, in addition to the presence of the poison--Its reappearance at present in Northern Africa (Bengazzi)--Modern theories as to its origin and mode of propagation, refuted by the histories of plague, cholera, and typhus--Murrains pp. 15–25 CHAPTER IV. View of nature acted on by the Hollander and Brabanter--Their struggle to overcome the difficulties of their position--Rise of the Dutch Republic, and of the School of Mechanical and Practical Science of Holland--Its influence over Europe and the world--Drainage of the Lake of Haarlem--Practical instances of the truth of the principle, that “when man interferes with nature, he must carry through the work to an issue”--How to convert a peat-bog into a healthy meadow, a dreary waste into a profitable, cheerful farm pp. 26–30 CHAPTER V. Sources of malaria--Various medical hypotheses refuted by Colonel Tulloch--Intermittents and remittents as they appear on the Western Coast of Africa and in Canada pp. 31–43 CHAPTER VI. 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.