“…New studies by Tsai and Hsu 4 have thrown further light on this question. If, as has been supposed, the added calcium and phosphorus arise from the bones, and if no other organs withdraw these elements from the blood during the period of augmented concentration under the influence of increased parathyroid hormone, the ratio of the increase of these elements in the blood should be the same as that in which thev occur in the 1 bone; namely, nearly 2:1. It was observed that, although the rise in phosphorus was slower than that of calcium and was maintained longer, the ratio of the absolute increase in the two substances at the maximum concentration in the blood after administration of parathyroid extract was approximately 2:1.…”