AN INTEREST in the influence of the central nervous system on the metabolism and excretion of electrolytes and water dates back at least to the middle of the 19th century, when Bernard1 observed a diuresis unrelated to glycosuria following puncture of a particular area of the floor of the fourth ventricle. His observation was confirmed and extended by Jungmann and Meyer.2 Since that time a considerable body of data has accumulated concerning the manner in which special structures within the central nervous system respond to and participate in the control of the volume and tonicity of the body fluids. The interrelationships among these several influences are quite intimate and so ordered as to provide a series of automatic adjustments that allow a high degree of precision in the control of the several dimensions of body fluid in health and in disease.
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