Rate of Recovery from the Action of Fluorite Rays

This paper is a report of some experiments upon the rate of recovery of Paramecium caudatum from the cytolyfic action of fluorite rays. The organisms were exposed to the radiation emitted through the fluorite window of the hydrogen discharge tube described in previous communications. 1,* The intensity of the radiation was such that an exposure of 8 seconds caused cytolysis in 57 per cent of the exposed organisms. In order to study the rate of recovery from the action of the rays, the entire 8 seconds of radiation was not given in one exposure, but in two portions of 4 seconds each, with a longer or shorter interval of time intervening between the two exposures. The relation between the length of this interval of time and the percentage of organisms cytolized was observed. The organisms used were from a pedigreed race of Paramecium cauda!um, cultured in drops of nutrient infusion on concave microscope slides. A single organism was placed in a small drop (measured to uniform size) and exposed to fluorite radiation on a special microscope slide provided with a fluorite window. The rays passed through the fluorite window of the microscope slide from below. After the exposure the small drop containing the organism was flooded with from one to two drops of infusion and the organism was transferred to a new concave slide and placed in a damp chamber for observation. The following day, the cytolized organisms were disintegrated, while the organisms which survived were active and