Abstract
It has been known for many years that on ligating the main vessel in the leg of an animal, the temperature in that limb will fall, and that at some later time it may return to normal with the development of a collateral circulation. In reviewing the literature, however, we have been unable to discover any work which would show just how soon such a response takes place, and in just what manner. Consequently, we undertook the following experiments.
As a means of determining the flow of the blood in the limb, and the efficiency of the circulation, continuous record was kept of the temperature of the foot after tying off the superficial femoral artery on the one side, using the opposite limb as a control. This was done by means of two thermo-couple junctions soldered within needles and pushed into the foot pads of the two hind legs, according to the method of Barney Brooks. 1 For these junctions, German silver and copper wires were used. The copper wire from each junction was connected with one pole of a two-way switch. The German silver wire from each needle was joined to another piece of copper wire to form the “cold” junction, and the two were passed through a glass tube in the cork of a thermos bottle. From this cold junction in each case connection was made by the copper wire to the corresponding pole of the switch. By throwing the switch to the right or left, the therrno-electric current from one or the other needle could be sent into a galvanometer whose deflections were first calibrated according to known variations of temperature in order to transform the results into temperature readings.
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