333 
electrogram as a sign of persisting basal negativity the heel of 
SamosLorr (marked by an A in the figure) cut into the retarded 
apical negativity. 
At 1 the base of the ventricle receives an induction shock a 
little after the apex of the negative 7-deflection. Four connected 
extra-systoles are evoked by it. From the accompanying ventricular 
electrograms it is evident that the conduction of the excitation wave 
through the ventricle is considerably slowed with each extrasystole. 
We infer this from the marked broadening of the R-deflections and 
the considerable change of the 7-deflections in a negative sense. 
The heel of SamoJLorF is clearly observable in each electrogram. 
When at the same moment of the ventricular period the base of 
the ventricle is again stimulated at 2, five connected extrasystoles 
of the ventricle will appear. Again during each extrasystole a con- 
siderable slowing of the conduction is conspicuous and may readily 
be read from the electrograms. At 3, however, an extra-stimulus 
touches the base of the ventricle much later, viz. a short time after 
the 7-deflection. Now only one extrasystole of the ventricle appears. 
During this extrasystole the rate at which the excitation wave is con- 
ducted through the ventricle is very likely slower than during the 
periodic ventricular svstoles, but decidedly not so slow as with the 
preceding ‘“‘gehdufte’” extrasystoles ’). 
The f-deflection is not nearly so broad as in the ventricular 
electrograms of the “‘gehaufte”’ extra-systoles. 
We also see at a glance the far slower conduction of the excita- 
tion wave during the “gehäufte” extrasystoles, for if we look at the Zi- 
deflections of the electrograms, it strikes us that the ascending lines 
are very clearly visible during the “gehäufte” systoles, while both 
during the periodic ventricular systoles and during the extrasystole 
at 3 they are reproduced by much thinner lines’). This implies that 
during the ‘‘gehaufte” extrasystoles the excitation wave is transmitted at 
a much slower rate from the starting point through the base of 
the ventricle than during the periodic ventricular systoles and the 
extrasystole at 3. It is evident, therefore, that during the extra- 
1) If we wish to compare the rate of the conduction of the excitation wave, it is 
evident that we can cumpare the extrasystole at 3 only with the first systoles of the 
“gehäufte” ventricle-systoles, for only with them the stimulus starts from a definite 
point i.e. the same point of the surface of the ventricle (viz. where the stimulant 
electrode stands). 
*) In the electrograms of frogs’ hearts it usually appears also, when the con- 
duction of excilation has been slackened, that the descending line of the R-deflec- 
tion is very steep or rather steep. In that. case the ascending line of the R deflec- 
_tion is less steep. 
22* 
