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of the ventrieulus cordis, as it is to be registered with numbers of 
animals and with man. 
The tops that are found in this atrioelectrogram are, as it were, 
analogous to the tops Q, R and P of the ventricle phenomenon 
and may respectively be called here P«, Pp, Pa- The tops Pa and Pp, 
like Q and R, which are analogous to them, fall in the ventricle- 
image wholly before the commencement of the muscle-contraction. 
In the electrocardiogram of man and animals derived indirectly, . 
we find, evidently on the ground of the P-elevation, only Pp expressed. 
Again by derivation of a heart of Rana derobed from ventrieulus, 
accordingly consisting only of sinus and atria, we get, a propor¬ 
tionately less large, but yet also a complicated electrogram of the 
atrium, as also by registration of the isolated atrium of the carp, 
where for example the first half of the atrioelectrogram shows a 
pronounced diphasic nature. 
It is also possible with a sample-object to derive both the atria 
at (he same time. The same thing I did also with the cut-out heart 
of Emys deprived of ventrieulus, where one electrode invariably 
found a place on the backside of the sinus, whilst two other electrodes 
respectively caused the derivation of the atriatops. By means of a 
swing-apparatus the galvanometer was connected with the sinus and 
respectively with one of the atria or with both. The electrogram of 
the one atrium obtained in this way differs at. such a derivation 
somewhat from the image got with the other atrium. The electrogram 
of the left atrium has a strong diphasic character; at derivation 
from the place of separation between the two atria with the back 
wall of the sinus, we get a less pronounced diphasic image, whilst 
the electrogram of the right atrium is only very feebly diphasic. 
The action-current of the heart is considered as a summary utterance 
of the electric negativities, which show themselves in the tissue 
successively in different places and at different times. This negativity, 
as Hermann formulated it, arises by the circumstance that every 
point of an irritable tissue at the moment of the stimulation stands 
in a negative relation to the parts that are in rest. At the derivation 
of such a tissue in different succeeding points we shall, therefore, 
every time get a deviating electrogram, but at the same time we 
shall be able to get an impression of the way which the proceeding 
stimulus has taken through the tissue. For this last purpose I 
have effected derivations of one atrium in different places, lying in 
regular prder. In this experiment I made use of the heart of Emys 
deprived of its ventricle and then derived with an electrode constantly 
from the sinus, whilst the other electrode (stor^electrodes with 
