280 Transactions of the Boyal Society of South Africa. 
the human being as figured by Einthoven/'' In making this record the 
right electrode has been connected with the right hand of the subject and 
the left with the left foot. The summits of the curve are lettered 
g, B, S, and T, by Einthoven. 
It has been shown by several observers that similar curves can be 
obtained from the hearts of cold-blooded animals, and indeed from an 
isolated chamber of such a heart, and we may assume that there is a 
characteristic electrical expression for the activity of cardiac muscle 
generally. My experiments have been carried out upon the heart of the 
tortoise, removed from the body after killing the animal by decapitation. 
The curve shown in Fig. 2 has been obtained in the following way : 
The heart of a large tortoise isolated from the body and continuing to beat 
Fig. 2. 
spontaneously was connected by two non-polarizable electrodes with the 
string galvanometer — Edelmann's large model of Einthoven's instrument. 
The right-hand electrode, which is connected with the lower end of the 
string of the galvanometer, and negativity of which, relative to the left- 
hand electrode, causes an ascent of the recorded curve, is applied on the 
ventral surface of the ventricle close to its right margin. The left-hand 
electrode, whose relative negativity depresses the curve, is applied to a 
corresponding point at the left margin. 
Using the nomenclature introduced by Einthoven for the human 
electrocardiogram, this curve may be said to show in its ventricular 
portion an initial or Q B S complex, of which the summits Q and B are in 
* Le telecardiogramme. Archiv. internat. d. Physiol., 1906, iv,, 132. 
