Askanazy1 in 1904 suspected a relationship between the parathyroid glands and the decalcification of the skeleton in a case of osteitis fibrosa; Erdheim2 in 1907 commented on the frequency of occurrence of hypertrophy of these glands in cases of osteomalacia, and Hoffheinz3 in 1925 noted the occurrence of decalcifying disease of the skeleton in twenty-seven of forty-five instances of enlarged parathyroid glands. However, the primary significance of tumors of the parathyroid to the skeletal lesion of generalized osteitis fibrosa was not recognized before Mandl's4 operative removal in 1925 of an adenomatous parathyroid gland and the alleviation thereby of the metabolic abnormalities in a case of this disease. Mandl's only rivals for the honor of originality are Schlagenhaufer5 and Weil.6 The former in 1915, apropos of two cases of this disease, in which tumorous parathyroid glands were discovered at necropsy, questioned the opinion, current at