Conductivity as a Measure of Vitality

The use of electrolytic conductance measurements in physiological research may be said to date back nearly a century. Eduard Weber at Halle in 18361 conceived that galvanic energy like other forms of energy might be useful in the human body, and that if this were the case there should be paths of differing conductivity through the tissues. His thorough and ingenious experiments command admiration, and his conclusions as to the epidermal locus of most of the electrolytic resistance of the body, and as to the effects upon it of warmth and moisture, are still valid. Mter Weber came du BoisReymond ~ who studied the resistance of muscle during contraction; Hermann 8 who showed that the resistance of muscle was greater across the fibers than along them; Ranke 4 who made careful studies of the decrease in resistance of plant and animal tissues upon death; and many others. In 1897 there appeared almost simultaneously a number of studies of the resistance of red blood cells s,e,~ which may be taken as the