IN the course of investigations on the phosphorus metabolism of the wax moth, Galleria mellonella, it was found that there is as much as 2–4 per cent phosphorus in the excreta of the larvae, of which only a small proportion is inorganic orthophosphate. The greater part, 60–70 per cent, is a labile phosphorus compound which is converted almost entirely to orthophosphate following 7 minutes hydrolysis at 100° C. in 1 N hydrochloric acid. As analysis of the honeycomb showed that it contained only orthophosphate, we had ground for supposing that the readily hydrolysable phosphorus in the excreta is formed in the larval body1.