1. It has been shown that, in vitro, the final oxidation product of 1:4 dioxan is oxalic acid, with diglycollic acid either as an intermediate stage or as a by-product.

2. Renal changes have been produced in rabbits by the intravenous administration of sodium oxalate, and renal and hepatic changes in rabbits and guinea-pigs have followed the application of ethyl oxalate to the skin. These lesions were similar in type to those produced by 1:4 dioxan.

3. The rabbits, in which ethyl oxalate was applied to the skin, showed a well-marked rise in the blood-urea content.

4. Renal changes of a similar type have occurred in rabbits after the intravenous administration of sodium diglycollate. These changes were less constantly observed, and were less in degree than those following intravenous sodium oxalate. Weight for weight sodium diglycollate appeared to be less toxic than sodium oxalate, when given intravenously to rabbits.

5. A possible method by which 1:4 dioxan may produce its effects is suggested, namely that 1: 4 dioxan is oxidised in the tissues to diglycollic and oxalic acids, which are neutralized to diglycollates and oxalates as soon as formed by the alkaline tissue fluids. It is possible that the relative amounts in which these oxidation products occur in the tissues, after the administration of 1:4 dioxan, may vary, and that the severity of the resulting lesions may depend upon this variation.