The greatest care must be given to the condition of the skin and intestines, if we wish to keep our kidneys in good order and prevent their deterioration. We must try to eliminate through the skin and intestines as many as possible of the toxic substances which otherwise would make their way to the kidneys and increase their work, and perhaps injure their epithelium. In this way we can save our kidneys for their time of need. Therefore, the skin and intestines should be kept in good working order. We must do all we can to maintain the function of the skin, and in several chapters of this book we have considered this question. We will only mention briefly that the invisible perspiration of the skin should be encouraged as much as possible. Damp and cold weather are apt to suppress it. In such weather our skin also gives off too much warmth, therefore we should be warmly clad, wool, especially for old persons, being best. Still more important is this when the kidneys are already damaged. For such persons a warn climate is advisable. By increasing the perspiration to sweating, products which are harmful to the kidneys may be eliminated. Hence such procedures will take work off the kidneys and rid them of injurious substances. The sweating should be done frequently, at least once a week, if we want to keep our kidneys in good condition. For fuller particulars on the hygiene of the skin, and also of the intestines, we refer to the chapters relative to these questions. ------------------------------------------------------------------------ CHAPTER XXIII. ON THE ELIMINATION OF TOXIC PRODUCTS THROUGH THE SKIN. THERE are some two and a half million small glandular formations—the sudorific glands—on the whole surface of the body in the subcutaneous tissue of the skin, from which issues a secretory tube somewhat of the nature of a corkscrew to the external surface of the skin. These glands are richly provided with blood-vessels, and a comparison may be drawn, to a certain extent, between the glomerules of the kidneys and these small glandular formations. The first receive certain substances from the blood and give it off through the tubules which carry away the urine, and the latter take both fluid and solid substances from the blood and eliminate it in the form of sweat through the excreting channels of the sudorific glands.