1590 
apex it was found to be perfectly. irritable during the entire diastole. 
Afterwards I injected 5 drops of a solution of veratrine 1°/, under 
the skin of the thigh. 
During the diastole the irritability gradually decreases, so that in 
the end, with an equal strength of the stimulation as before the 
injection, | ean only during the pause obtain extra-systoles which 
are much smaller than the systoles of the normal rhythm. The 
frequency of the systoles diminishes somewhat. About half an hour 
after the injection halving of the ventricle-rhythm begins. After the 
heart has executed a few  systoles in this halved rhythm, L apply 
an induction stroke at the end of the diastole. By this stroke the 
normal, twice as rapid rhythm is restored (vide fig. 1)*). This can 
be explained as follows. 
V 
Fig. 1. 
Whilst the ventricle is pulsating in the halved rhythm, the pauses 
between the ventricle-systoles have become much longer. This causes 
the residue refractory-stage to decrease, because the ventricle-muscle 
can better restore itself during the lengthened pauses. Yet the normal 
rhythm does not return, because the periodical refractory-stage has 
increased in duration. The lengthening of the periodical refractory- 
stage is a direet consequence of the enlargement of the systoles. 
The result is then, that the total refractory-stage has not yet diminished 
in duration, as long as the halving of the ventricle-rhythm lasts. 
Ll expressed this in a previous communication by observing, that the 
increase of size and duration of the systoles in the halved rhythm 
captivates the ventricle in its own rhythm. If now, at the end of 
the diastole, I apply an extra-stimulatlon (at QO) an extra-systole is 
caused, which is much smaller, because the pause that immediately 
1) All figures have been reduced. The figures 1 to 6 included, belonging to 
the same heart, have not been reduced in the same measure. The distance between 
the stimulation-signal and the time-signal, which is equal in the original rows of 
curves is unequal in these figures. This allows us to judge of thedifferent degrees 
of reduction. 
