Biological Investigations with Radioactive Calcium and Strontium.

The metabolism of calcium and strontium has been studied on normal animals with the radioactive isotopes of those elements. Uptake in the skeleton of different salts of strontium has been compared. These experiments have furnished two practical findings: (1) a method to irradiate the skeleton selectively for therapeutic purposes, (2) the secondary production of appreciable amounts of a long-lived radioactive yttrium, the most likely among the artificial radioactive elements now known, which may be substituted for radium as a penetrating gamma-ray source.