Most authors who have written on the subject of infantile tetany connect the cause with a disturbance of the calcium metabolism, the greater number believing it to be due to a deficiency of calcium in the tissues. Stoeltzner1 and his co-workers believe there is a stagnation of calcium in the tissues. Cybulski2 and Schabad3 are confirmed that the calcium excretion is not regularly increased in tetany; yet the latter finds that on giving cod liver oil and phosphorus, there is a gradual reduction of electrical irritability with simultaneously an increased calcium retention. Schwarz and Bass4 failed to find any lessening of calcium retention. MacCallum and Voegtlin5 observed that in parathyroidectomized dogs the injection of calcium and magnesium salts stops all symptoms of tetany and that the injection of sodium and potassium salts has the opposite tendency. In addition to this they found a reduction of