As we have already described in previous articles of this series of papers, the spinal parasympathetic has a vasodilator effect upon the vessels of the systemic circulation-vessels of skin, stomach and intestine, pancreas, kidney, suprarenal, testicle, etc. We have, therefore, been the more surprised to find that the spinal parasympathetic has not a vasodilator, but a vasoconstrictor effect upon the pulmonary vessels.Method of Experimentation. Wishing to stimulate independently the ventral and dorsal roots of the pulmonary outflow, i.e. of the upper and middle parts of the thoracic cord, we found that there was not enough room to do this without first severing the connexion of one or other of them with the region of the cord from which they originated. Accordingly we exposed in the dog the region in question, and on the one side cut three or four of the ventral roots and on the other side both dorsal and ventral roots, and then stimulated the cord with the view of getting the responses of the dorsal roots. In like manner, in order to get the responses of the ventral roots we cut the dorsal roots on one side and both roots on the other side. For stimulation we generally used a pair of hookelectrodes with the two poles widely separated and fixed at either end of the exposed part of the cord. The poles were securely tied to the dura mater by thread. As the distance between the poles was considerable we used comparatively strong faradic currents, the distance of the secondary coil of the inductorium being usually 4 to 5 cm. with a 3*5-volt battery. Before going further the exposed portion of cord was crushed at its upper and lower ends in order to prevent the rest from being stimulated when the current was applied.The animal having been fixed on its back and artificial respiration * s-IL-. a ss-* -
340Ken Kure, Ryoji Ikeda, and Fujio Sakurasawa applied, the vagi were in some cases cut, in others left intact. The thoracic cavity was then opened, the condition of the lungs noted and compared with one another: this being done we separated off with a,Kocher clamp a small piece of lung on each side for histological investigation. In some experiments we stimulated the peripheral stump of the cut vagus and also the stellate ganglion. An experiment of this kind can only be successfully performed if the animal is kept sufficiently warm. As it was difficult to satisfy this condition we always carried out the experiments in hot summer weather (at a temperature of over 31°C.), and since such days are rare with us we had to make use of three summer vacations for this purpose. After stimulation we clamped off corresponding portions of the two lungs and removed these for histological examination. Before being fixed the separated pieces were photographed; they were then fixed with formalin, embedded in celloidin, and the sections cut and stained with h em atoxylin-eosin.RESULTS.FIRST SERIES OF EXPERIMENTS. STIMULATION OF DORSAL ROOTS ONLY. Experiment 1.-Both roots of the 6th, 7th, 8th, and 9th thoracic segments were cut on the righ...