. American journal of physiology. de solution. Injection pressure. Vein pressure. Injection pressure. Vein pressure. 40 60 80 400 100 120 140 120 80 The observed divergence could not be explained by obstructionsin the vein; the continuance of the vein flow up to the maximal veinpressure shows that if any obstruction exists, it is only partial, anda partial obstruction would only delay, never prevent, the final level- ^ In this and in the following , the arterial pressures are representedby the heavy, straight, ascending line. The vein and ureter flow
. American journal of physiology. de solution. Injection pressure. Vein pressure. Injection pressure. Vein pressure. 40 60 80 400 100 120 140 120 80 The observed divergence could not be explained by obstructionsin the vein; the continuance of the vein flow up to the maximal veinpressure shows that if any obstruction exists, it is only partial, anda partial obstruction would only delay, never prevent, the final level- ^ In this and in the following , the arterial pressures are representedby the heavy, straight, ascending line. The vein and ureter flows are plotted onsuch a scale that the maximum flow coincides with the maximum injection pres-sure; the oncometer curve is represented in same manner. The curves for thevein and ureter pressure represent the actual values. 2 We .shall always limit ourselves to the reproduction of illustrative data,omitting the duplicate experiments which we have made to exclude accidentalvariations. Perfusion Expcrim€7its on Excised Kidneys. 255. ling of the pressures. The only way in which the lower vein pres-sure can be explained is by a leak in the system. That such a leakexists, is shown by the slow streamof bubbles through the reservoir,occurring even when the renal veinis absolutely occluded (some 5 minute). The leakage is notthrough the ureter, for the ureterflow is practically abolished bythese high vein pressures; but anactual escape of fluid from the cor-tex of the kidney can always benoted. The vessels which leavethe capsule of the kidney to forma collateral circulation are nodoubt the anatomical seat of thisleak. The divergence can be imitatedon an artificial model, constructedas in Fig. 2. Experiments with this modelgave the following results: Adivergence of the arterial andvenous pressure, in the form of astraight line, was obtained when-ever a leak was introduced intothe system. Altering the condi-tions affected merely the degreeof divergence, as follows: a. The differen
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