1591 
precedes, is considerably reduced. Consequently the periodical refract- 
ory-stage of this extra-systole is much smaller than with the systoles 
of the halved rhythm. For that reason the total refractory-stage 
during this extra-period has become much shorter than during the 
periods of the halved rhythm. 
After this one preceding, shorter pause the residue refractory- 
stage has of course not yet strongly developed itself. It increases 
only by accumulation, when the ventricle has executed a few systoles 
in the normal rhythm. Consequently it is clear that the total refractory- 
stage during the extra-systole is shorter than during the systoles of the 
preceding halved rhythm. And therefore the next following normal 
“Krregung”’, coming from the auricle, causes a systole in the ventricle. 
But this systole is also again smaller under the influence of the preceding 
short pause, so that also after this systole the next following impulse 
coming from the auricle causes a systole of the ventricle. Thus the 
normal, twice as rapid rhythm continues, till, by increase of duration 
of the residue-refractory-stage, the total refractory-stage has been 
lengthened so much, that this rhythm can no longer be maintained. 
In our present case the normal rhythm continued during 16 systoles, 
and then changed into bigeminus-groups alternating with trigeminus 
ones. This bigeminy passes into the halved rhythm. By an induetion- 
stroke at the end of the diastole I convert this halved rhythm into 
bigeminy. When this bigeminy has lasted for about two minutes, I 
apply an extra-stimulation to the apex ventriculi just before the end 
of the diastole of the first large curve of a bigeminus-group (fig. 2) '). 
Fig. 2. 
The extra-systole that is oceasioned then, is a little smaller than 
a 2nd systole of the bigeminus-groups, and the pause after it is a 
little longer than the pauses between the bigeminus-groups. The 
next following systole is thereby somewhat enlarged, so that now 
the halved rhythm ensues. Now the total refractory period of each 
systole is of too long a duration for another systole to follow after 
it with the interval of the normal rhythm, as is the case with the 
1) In the figures 2, 4, 7 and 8 the signal-oscillation, indicating the stimulation 
is a little too small. By adding an arrow (f) I have i-dicated more exactly the 
moment, when the stimulation was applied. 
