PARATHYROID GLANDS 639 



the calcium question, but general interest in the subject of the relation of 

 tetany to calcium metabolism was excited by the important paper of Mac- 

 Callum and Voegtlin, published in 1909. In their article, these American 

 investigators expressed the opinion that the withdrawal of calcium from 

 the nerve cells leaves them in a state of hyperexcitability, which can be 

 made to disappear by supplying the body with a solution of calcium salts. 

 Tetany, they asserted, may be regarded as an expression of hyperexcit- 

 ability of the nerve cells, due to some such cause as calcium deficiency 

 in the nerve cells. They found that the injection of a solution of a salt 

 of calcium into the circulation of an animal exhibiting the symptoms of 

 tetany promptly checks all these symptoms and restores the animal to an 

 apparently normal condition. They asserted further that injections of 

 magnesium salts have a similar effect, though the effect is masked to some 

 extent by the toxic action of these salts. The injection of solutions of salts 

 of sodium or potassium, even of the alkaline salts of sodium, on the con- 

 trary, intensifies, according to MacCallum and Yoegtlin, the symptoms 

 of tetany. As a result of their own studies and of the studies reported in 

 the literature, these authors felt convinced that there is a marked reduc- 

 tion in the calcium content of the tissues, especially of the blood and brain, 

 in tetany and that there is an increased output of calcium in the urine and 

 feces when the syndrome develops. MacCallum and Voegtlin further 

 pointed out that, though the signs of acidosis are present in the urine in 

 tetany, the symptoms of tetany are not ameliorated by the injection of 

 alkaline sodium salts into the blood. The acidosis may, they thought, be 

 important in draining the tissues of calcium salts. The same investi- 

 gators also asserted that the parathyroid secretion must in one way or an- 

 other control the calcium exchange in the body, and suggested that, in the 

 absence of normal amounts of parathyroid secretion, there may be formed 

 certain chemical substances that, combining with calcium, abstract it from 

 the tissues and lead to its excretion. The presence of normal amounts of 

 the parathyroid secretion prevents, they believed, the appearance of such 

 substances. Though they could not determine the mechanism when the 

 action of the parathyroid secretion is lost, its results (namely, the impover- 

 ishment of the tissues with respect to calcium and the subsequent develop- 

 ment of a hyperexcitability of the nervous system in tetany) they believed 

 to be proven. And they surmised that the same explanation could be ap- 

 plied to the pathogenesis of spontaneous tetany in human beings. In this, 

 as in experimental parthyroidectomy, there must be a drain of calcium for 

 physiological purposes, or, at any rate, there must be in it some condition 

 that results in a withdrawal of calcium from the nerve cells. They sug- 

 gested that, in this spontaneous tetany of human beings, the parathyroid 

 gland may be only relatively insufficient, but the hypoparathyroidism prob- 

 ably accounts for the calcium drain. 



These views of MacCallum and Voegtlin seemed not to be out of ac- 



