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the ventricle and again by jerks. Thus the excitation wave keeps on 
circulating through the ventricle like an ignis fatuus, and fibrillation 
is checked only when it strikes on a refractory region. Then 
the post-undulatory pause sets in, which however may also be 
absent. (Fig. 1 after 2 in the second row). 
After an extra-systole, elicited later in the excitable period, the 
excitation-wave does not begin a second course, because then it is 
checked by the refractory stage, which with this extra-systole is 
of longer duration. The same relations exist with the normal rhythmie 
systoles. If in this case the refractory stage were absent or much 
shorter, the excitation-wave would always continue its course in the 
closed muscular system of the ventricle, which would not be able 
to pulsate rhythmically under the influence of the sinus-impulses. 
According to my theory, therefore, fibrillation of the heart is 
brought about by a non-coördinated contraction, not as WINTENBERG 
conceived this; viz. that sundry sources. of contraction are function- 
ating independently; according to my theory the various regions of 
a ventricle contract successively and an “Erregung” being once 
elicited may pass through a ventricle several times running; the 
ventricular delirium consists of a string of fractionated ventricular 
systoles. For fibrillation two conditions must be fulfilled at the 
moment when it originates: 
1. The refractory stage must be shortened. 
2. The conductivity of the stimulus through the ventricle must 
be insufficient. Both conditions are fulfilled in my experiments. 
Directly after the close of the refractory stage the metabolic condition 
of the ventricle is bad, contractility is slight, so the refractory stage, 
accompanying a contraction, is short; moreover the conductivity 
through the ventricle is insufficient. 
WiINTERBERG and Rorpercer believed that the only essential con- 
dition for the origin of fibrillation was a much shortened refractionary 
stage. This is true if only conductivity is also bad. Only then will 
the phenomenon come forth. 
Now the question arises, why after digitalis poisoning of the 
1) Incessant fibrillation may succeed when the “Erregung”’ after one circulation 
always arrives at the starting point again at a moment when the recovery is still 
insufficient. Thus the excitation-wave may be emprisoned in a ventricle and every 
time renew its course. Especially when (as in Fig. 3) the delirium becomes regular; 
then the chance of a spontaneous termination is little, as, when the excitation-wave 
has gone through the ventricle some times in succession in the same way, this 
may be repeated every time without the “Erregung” being checked by a refractory 
region. 
