We have studied on the rate of excretion of colloids in the morning urine of normal male subjects by the method of Donagio's reaction modified by one of the authors, Yamazoye. The results obtained were as follows.
1. The rate of excretion of urine colloids increased in the morning, coner or latter, when the subject-waked up and stayed quietly in bed. We prorse to call this phenomenon “morning colloid tide”.
2. Becaus this takes place in the morning w hen the subject keeps awake all night it seems probable that the “morning colloid tide” has no direct relationship with the waking up itself.
3. The “morning colloid tide” occurs generally associated with the temporary increase of creatinine excetion, but not necessarily with the morning alkaline tide and diuresis.
4. It is suggested that the “morning colloid tide”, at least in part, is due to the increase of renal function.