Physiology. — “On Fibrillation of the Heart.” (Part Ill). “Ven- 
tricular Fibrillation and “Gehiüufte” Extrasystoles of the Ven- 
tricle excited by the “Eriegung” consequent on an Artificial 
Auricular Systole.’ By Dr. S. pu Boer. (Communicated by 
Prof. WeRTHEIM SALOMONSON.) 
(Communicated at the meeting of April 23, 1920). 
IND 
In the first Part I have described experiments with the bled frog’s 
heart in which ventricular fibrillation was excited through the ad- 
ministration of a single inductionshock to the ventricle directly after 
the conclusion of the refractory stage. 
I have observed since, that a direct induction shock is unnecessary, 
as fibrillation occurs also when excitation affects the ventricle directly 
after the conclusion of the refractory stage. We can carry this into 
effect by administering an induction shock to the auricles of the 
bled frog’s heart at the beginning of their excitable period. After 
the auricular extrasystole thus excited, the excitation proceeds along 
the atrio-ventricular paths to the ventricle. This excitation can reach 
the ventricle directly after the close of the refractory stage, only 
when the shock is administered to the auricle as soon as possible. 
This is instanced by the following experiment. In fig. 1 the suspen- 
sion curves of the ventricle (V) and the auricles (A) of a frog’s 
heart are illustrated, 15 minutes after the bleeding. Between the 
curves of 1a and 15 two heart-periods have fallen out. At the 
deflection of the signal in fig. la the auricles received an induction- 
shock, a short time after the conclusion of the refractory stage. 
Hereby an extrasystole of the auricles was generated. The excitation 
then reaches the ventricles at the end of the diastole (i.e. at a moment 
when the refractory stage of the ventricle has been concluded for 
some time), so that a premature ventricular systole is the consequence. 
Subsequently the auricles and the ventricle resume the ordinary 
rhythm. 
In fig. 16, on the contrary, the auricles were stimulated at 1. in 
the beginning of the excitable period, by which an extrasystole of 
the auricles is engendered. After this the excitation reaches the 
