Artificial Radio-Activity and Neutron Rays in Biology and Medicine *

During the past few years, physicists in this country and abroad, in their studies on the atom and the atomic nudeus, have made contributions which, it already appears, will have important practical applications in biology and medicine. To be specific, more or less as a by-product of their studies to learn more about the building-blocks of matter, they have produced radio-activity artificially and a new form of radiation with intense biological activity-the neutron. Enough exploratory work has been carried out to show that a distinctly new field in fundamental biological investigation is opened up. Some of these developments will be summarized here. It is not necessary to point out the importance to dinical and experimental medicine of the naturally occurring radio-active materials and x-rays. Physicists have now made numerous other elements artificially radio-active, in fact, the list indudes a majority of the elements of the atomic table and is enlarging every day. Elements of obvious interest in biology are: sodium, phosphorus, potassium, sulphur, and iron. Thus we have for use in biology, radioactivity in many of the elements and, in addition, another form of penetrating radiation, neutron rays.