1. Hydras were left for 24 hours in solutions of MgSO4, glutathione and MgSO4 + glutathione after exposure to 25,000 r x-rays. Only the hydras in MgSO4 alone were significantly protected against the effects of the radiation.2. Hydras were exposed continuously to MgSO4, glutathione, and MgSO4 + glutathione solutions after 4500 r. The rates of budding in each solution were determined. It was found that:(a) Forty-five hundred r inhibited the budding of hydras significantly.(b) Magnesium sulfate and MgSO4 + glutathione stimulated budding of non-irradiated hydras while glutathione alone did not.(c) Magnesium sulfate alone did not significantly modify the inhibitory effect of the radiation on budding.(d) Glutathione alone partially reversed the inhibitory effects of the x-rays.(e) Within a fairly wide range of concentrations of MgSO4 and glutathione, the two agents together restored the budding rate of irradiated hydras to that of the non-irradiated animals in standard saline.