The enthusiasms that have been aroused by the demonstrable physiologic potency of irradiation with ultraviolet rays generated in various ways call for restraint before they are permitted to promote therapeutic procedures that may presently be discovered to be ill advised. It is better that disappointments should precede rather than follow their use. Irradiation cannot be rationally employed until its possible effects on the organism are thoroughly investigated in many directions. The antirachitic effects of exposure to ultraviolet rays are so striking and easy of demonstration that there has been a tendency to expect only beneficial results from irradiation, regardless of intensity and "dosage."
Some of the effects on the blood and circulation have already been determined with sufficient accuracy to justify the proposed precautions. Not long ago it was shown by Miles and Laurens1 that the exposure of dogs to carbon arc radiation may give rise to variable results