536 
late in the excitable period. Accordingly after the auricular extra 
systole thus excited, the ventricle presents a premature systole. The 
experiment will succeed better when at the fourth deflection of the 
signal the shock is repeated during a post compensatory systole at 
an earlier moment. Now an extra-systole of the auricles originates 
in the beginning of the excitable period. The excitation reaching the 
ventricle after this, comes early enough to evoke a brief fibrillation. 
_As before, the auricles exhibit some anomalies. At the sixth deflection 
of the signal the auricles are once more stimulated during a post- 
compensatory systole. This time this stimulus affects the auricles a 
little earlier still than the preceding time. After this extra systole 
of the auricles the ventricle begins to fibrillate for a longer period 
under the influence of the excitation. During this fibrillation the 
auricles present anomalies similar to the preceding. 
In Fig. 3 the curves show that the contractility of the ventricle 
was still intense’), although through indirect stimulation the ventricle 
could be made to fibrillate. At 1 the auricles receive an induction 
shock, which gives rise to an extrasystole of the auricles. 
This is followed by a premature ventricular systole with the ordinary 
a—v-interval. At 2 the extra-stimulus is repeated directly after the 
postcompensatory sytole, which is succeeded by a small extra-systole 
') With all curves taken with double suspension, the ventricular curves were 
registered with a five-fold magnification. 
