Researches on the Circulation Time in Organs and on the Influences which affect it

SOME time ago' I described a method of measuring the circulation time which I believe to have great advantages over the method of Hering in the cases to which it is suitable, and which I have found especially useful in studying the circulation in organs like the kidney, lungs, liver, intestines, etc. I wish here to give a preliminary account of some of the work I have done in this way during the past two years, without either quoting or discussing the results in detail, or making more than incidental references to the literature of the subject. The experimental arrangements will, however, be described with some minuteness. In future papers I hope to treat the matter more fully, with the aid of the considerable amount of material already in my possession and of that which I may be able further to accumulate. A discussion of the theory of the method, a critical estimate of its value, and an examination of possible objections to it will be attempted in one of these papers. The principle on which the method is based is as follows. Since the electrical conductivity of blood is practically that of a solution of the salts in it, it can readily be altered by the injection of a solution of common salt of sufficient strength. The alteration will travel on with the velocity of the blood stream, and the arrival of the altered blood at any point of the vascular system may be detected by an easy galvanometrical observation, without the necessity of opening the blood-vessel. If a pair of unpolarizable electrodes be put in contact with the vessel between which and the point of injection the circulation time is to be measured, and connected with the ordinary Wheatstone's bridge arrangement, the balance will be disturbed as soon as the altered blood has reached the piece of vessel between the electrodes;