The effects of further irradiation of the radiation products of ergosterol

The effects of ultra-violet radiation upon ergosterol have been studied by many workers, but the results have been difficult to interpret owing to the fact that certain of the products of radiation are themselves changed by further exposure, at a rate greater that the velocity of change of ergosterol itself. Windaus, Westphal, Werder and Rygh (1929) have carried out some experiments in which the irradiation products of ergosterol were freed from unchanged ergosterol, and then re-radiated. They used the same source of energy (a magnesium spark) for both first and second irradiations, and obtained results of some interest, but still difficult to interpret.