1O77 
tions for the formation of a postcompensatory systole as wide as 
possible (according to LANGENDORFF) are then most favourable. 
The irritability of the heart-muscle during the diastole has much 
improved again during the pause. This appears from the fact, that 
the next-following systole, after the posteompensatory one, occurs in 
the diastole of this posteompensatory systole. The ventricle conse- 
quently is now susceptible of the weak physiological irritation 
coming from the auricle, whilst, two heart-periods before during the 
diastole, it was still insusceptible of a much stronger, artificial 
stimulation. By artificial irritation in the diastole of the post-com- 
pensatory curve I could again bring about extra-systoles, which did 
not occur when, with the same strength of stimulation, I irritated 
at the same moment of the diastole in the normal rhythm. The 
refractory period however can be enlarged during this great systole 
without extending to the diastole. Experiments, in which I noted 
likewise the action-currents, taught me, that during the extra-pause 
the ventricle neither produced action-current. 
[ repeated this experiment more than a hundred times. An 
extra-stimulation occurring somewhat later caused again an extra- 
systole (vide Fig. 1 the 7 systole of the second curveseries). 
In a later period of the poisoning the rhythm of the ventricle is 
halved, after the extent of the systoles has first diminished. The 
cause of this phenomenon lies in the prolongation of the refractory 
period and of the a—vy-interval. An auricle systole falls consequently 
at last in the refractory period of the preceding ventricle-systole, so 
that then every 2" auricle-systole remains unanswered by the ventricle. 
[Ne 
