In a previous paper from this laboratory (by Fowler and Hawk) data were presented indicating that copious water-drinking with meals was accompanied and followed by a decrease in the bacterial content of the feces. It was there shown that during a preliminary period in which a uniform diet was supplemented by a small water ration, that 5.3 gm. of dry bacteria was excreted per day, a value which was decreased to 4.6 gm. per day during an interval of five days in which the water ingestion was increased 1,000 c.c. per meal. Furthermore, data were presented which showed a further decrease in the daily output of bacteria during a postwater period of low water ingestion, the daily value for this period being 3.3 gm. In keeping with the figures for the excretion of bacterial substance in the feces were the results secured for bacterial nitrogen. These data showed