CONNECTED WITH THE BEAT OF 'J’HE MAMMALIAN HEART. 
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ments in the electrometer were arrested, showing that they were due to ventricular, 
and not to auricular, contraction. 
Experiment 9 is, in two respects, a typical one : it is representative of many others 
which I have made, in which the heart is led off from the mouth or from an eye, 
and from the rectum or from an inferior extremity; electrical variations are thus 
unfailingly demonstrated of a character which is illustrated in photo. 2. 
Photo. 2. 
Electrical vaiiations of Cat’s heart, with body intact, and led off from mouth to Hg, 
from rectum to HtiSO^. 
Cat’s heart, exposed immediately after death by chloroform, and injured at the apex by crushing. Led 
off from auricle to Hg, and from apex of ventricle to H^SO^. Variations sS.s^sS (read from right to 
left; s = negativity of auricle, S = negativity of base of ventricles). 
It al so shows that the variation observed with peripheral leading-off points is 
exclusively ventricular. I have since repeatedly observed (with special facility when 
the auricles and ventricles have happened to beat at different rates) that, for the 
demonstration of any electrical change accompanying auricular contraction, it is 
necessary that one of the electrodes should be in actual contact with the auricles, 
and that, as soon as it is shifted to a distance, the auricular variation is lost. 
Photo. 3, taken with one electrode in contact with the auricle while the other was 
Photo. 3. 
