STUDIES ON THE ARNETH COUNT.—XVI. THE DEFLECTION OF THE COUNT BY IRRADIATED ERGOSTEROL

1. The results of Kennedy and Thompson on the deviation of the Arneth count by ultra-violet irradiation are confirmed. 2. The deflection resulting from the parenteral administration of irradiated ergosterol is closely comparable to that produced by direct ultra-violet rays. 3. The blood-calcium level is raised both by direct irradiation and by administration of irradiated ergosterol. 4. While a combination of irradiated ergosterol and ultra-violet rays produces an additive effect on the blood-calcium level, no such additive influence is exerted on the Arneth count. 5. In the control series no deflection or change in the blood-calcium level was produced by either filtered ultra-violet light or by non-irradiated ergosterol.