DIRECT VERSUS TRACER MEASUREMENT OF TRANSFER RATES IN A HYDRODYNAMIC SYSTEM CONTAINING A COMPARTMENT WHOSE CONTENTS DO NOT INTERMIX RAPIDLY

The working basis for the measurement of transfer rates between compartments developed in a preceding paper by Wrenshall is demonstrated for a closed hydrodynamic mammillary system in dynamic equilibrium. Rapid uniform intermixing of the water in one of the peripheral compartments was prevented by the presence there of glass tubelets. Rates of water transfer were measured directly with a graduate cylinder and stop watch, and calculated by means of equation [9] of the preceding paper, using crystal violet dye as tracer. It is clearly demonstrated that to measure transfer rates between the central compartment and the non-uniformly mixing peripheral compartment, it is necessary to extrapolate all tracer measurements to lime of tracer addition to the central compartment. The amount of water contained in the central compartment was measured in the same experiment both directly and by tracer dilution. The procedures and problems involved in performing the above model experiment are compared with those encountered in the tracer measurement of transfer rates and compartmental contents in living mammillary systems.