182 
DE. A. D. WALLER ON THE ELECTROMOTIVE CHANGES 
to the electrometer from leg and mouth. And I may add that I also experimentally 
verified the fact that, while potential at mouth agreed with sign of pole at base, 
potential at rectum agreed with sign of pole at apex. 
In the preceding experiments the electrical variations of the heart were observed by 
leading off from remote points with the thorax opened, and with the heart therefore 
lying in contact with the tissues by its posterior surface only. The next step was to 
determine whether the variations can be observed on the intact animal, with the 
heart in contact with its normal surroundings. 
Experiment 9.— Cat. April 23rd, 1888. Death by chloroform. Led off to the 
electrometer by electrodes in the mouth and in the vagina. Variations observed 
synchronous with the heart’s beat, but too rapid to allow their character to be deter¬ 
mined. Apparently each variation was double, but it was impossible to tell which 
was the first and which was the second phase, the rhythm being— 
. snsnsns . 
Both vagi exposed, isolated, and divided. Excitation by induced currents of either 
vagus abolished the variations, the right vagus being in this respect more efficacious 
than the left. After each period of arrest, the first movement of the mercury in 
the electrometer was closely watched ; it was southwards (with mouth to HoSO^ and 
vagina to Hg); graphically expressed, the effects were— 
Similar results were obtained with the electrode transferred to the eyeball 
and with the subsecpient transfixion of the heart by a pin connected with the Hg of 
the electrometer. This was between ten and fifteen minutes po-^t mortem. The heart 
was now exposed by opening the thorax, and vagus effects were repeatedly obtained 
up to about half an hour^rort mortem, excitation of the right vagus being uniformly 
the more effectual. Towards the end of the experiment the following point was 
noted : excitation of the right vagus arrested the movements of the auricles and of 
the ventricles ; excitation of the left vagus arrested the movements of the ventricles, 
and not those of the auricles, wliich continued to pulsate.In both cases the move- 
* This was one among a considerable variety of effects which vagus stimulation may produce upon 
the contractions of the Mammalian heart ^ost mortem. 1 have seen vagus stimulation under these 
circumstances entirely without effect upon aiiy of the four chambers, or followed by comjjlete ai’rest of 
the whole organ, 6T by arrest limited either to the auricles or to tlio ventricles. I have also seen a 
delirium cordis entirely uhintluenced by, or enlircly suspended during, vagus stimulation. 
