VARIOUS PAPERS XX. AN EXPERIMENT IN SANITATION-COLLECTION OF RAIN-WATER-DISPOSAL OF SLOP-water. XXI. MILK IN ITS RELATION TO HEALTH AND DISEASE 251 THE EARTH IN RELATION TO THE PRESERVATION AND DESTRUCTION OF CONTAGIA* CHAPTER I EARTH-PATHOGENIC SAPROPHYTES-TETANUS THAT which we commonly speak of as earth, soil, or humus, is largely composed of excreta and the dead remains of animals and vegetables, which, as the result of fresh biological processes, are either returned to the bodies of living vegetable organisms, or, after becoming mineralised and soluble, are washed downwards by the rain and ultimately find an exit in the sea. It is obvious that not only does 'earth' vary in composition with the varying conditions of subsoil, climate, flora and fauna, but that earth' must undergo seasonal variations necessitated by the vigorous upgrowth in the spring or the decay of the fall-the heat and drought of summer or the flood and frost of winter. The interstices between the particles of * Being the Milroy Lectures delivered before the Royal College of Physicians, London, in 1899 (Chapters I. to XIV. inclusive). |