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Blood runs with varying amounts of flow per unit of time through the heart and blood vessels different in width and length in the different organs. The problem here is to study the dilution process of the substances which are supposed not to pass the walls of blood vessels,when they are injected at some point of this circulatory system in various wave forms of in-put.It might be most desirable that the theory of dilution process should be constructed on the basic law of physics,such as hydrodynamics of viscous fluid in the heart and vessels,and diffusion theory of the injected substances.It seems however that the study in this direction will be difficult at the present stage of progress of physics and of our knowledge about the physical features of the heart and blood vessels.For instance we do not know how the peripheral arteries,arteriols and capillaries are connected with each other or what are their elastic coefficient,and rheologic features of the blood are also far from being completely known.It is therefore hardly acceptable that the result of the experiment with a model of circulation could precisely predict any concentration curve of the injected dye in the circulatory system of the living body. HAMILTON et al1)found in a one-way perfusion of the heart and lungs that decending limbs of the curve of dye concentration against time plotted as a straight line on a semilogarithmic paper.This finding has been considered as a proof of enabling a calculation of both flow and volume by extrapolating the initial exponential segment.They stated that the non-exponential curves obtained in perf using only through the lungs,are changed into exponential when they are attached to the mixing chamber of anatomical size relations.

A CRITICAL STUDY OF HAMILTON-STEWART'S PRINCIPLE FOR THE ANALYSIS OF HEMODYNAMICS