Abstract
The spontaneous variations of the 24-hour excretion of trypsin inhibitor in urine have been examined in 62 normal persons or persons with indifferent diseases in one period of 3 consecutive days and in 3 normal persons in more periods distributed over larger spaces of time. Within a period of 3 successive days, the individual sustains a level of excretion with relatively small, apparently fortuitous variations from day to day, characterised by the average coefficient of variation 0.32. From one period to another the individual changes levels of excretion. These latter Variations are in general moderate although they can be much larger than the variations found for the single period. The variation in the same person from one period to another never reached the magnitude of the differences which can be seen between different persons.