“On a dog of middle size I opened the trachea and inserted into it a glass tube.… Then I dissected out and isolated the nervi vagi; the animal was laid on its back and the thorax opened by cutting through the cartilage of the ribs and entirely removing the sternum. The pericardium was now opened … and artificial respiration introduced. Partly through the suffocation and partly through pain and terror, the movements of the heart grew very slow, small, and irregular … but after the artificial respiration had commenced, they got more vigorous.… Five minutes after I cut asunder both nervi vagi, at which operation the animal uttered no sign of pain. A minute after the movements of the heart were so greatly accelerated that it became difficult to count them.… It struck us that the heart seemed to have grown smaller than before we cut asunder the nervi vagi.… Then I stimulated (irritated) the peripheric ends of the cut nervi vagi with Neif’s electric apparatus. Almost immediately the heart stood still in diastole.… The movements of the heart recommenced and grew more rapid and vigorous than ever, but this soon passed away. The ends of the nervi vagi were for a second time stimulated … and this proceeding was repeated six times, always with the same result.… The pain, which otherwise results from the nervi vagi being cut asunder, was eliminated, because the far greater pain, occasioned by the opening of the thorax, had, as every very painful operation will do, diminished the sensitiveness of the animal so much that it gave no evidence of pain at the cutting asunder of the nervi vagi. Without introducing artificial respiration at the opening of the thorax, I have repeated this experiment scores of times, and always with the same result.”--Panum, _Scand. Medical Bibl._, 1857. “26th Ex.: I had opened the thorax of a dog and kept its life up by artificial respiration, having also cut the nervi vagi. Everything had gone as we desired. The heart worked vigorously and regularly, and the animal had full consciousness and sensitiveness. On applying the electrodes of Neif to the heart, its regular movements ceased immediately.”--_Ibid._, p. 134. Prof. Panum states that he has “employed” a great number of animals in experiments of transfusion and injections of putrid humours. For experiments on death by embolism he has employed some eighty dogs and rabbits.--“_Experimental Observations_,” _Virchow’s Archiv._, Vol. XXIX., 1864.