1594 
heart-veins. These investigators have not been able to explain this 
phenomenon. It is certainly peculiar that I myself, in the beginning, 
found this conversion of rhythm only by extra-stimulations applied 
at a special moment of the diastole. The cause of this conformity 
—for in the beginning I made these experiments without being 
acquainted with the investigations of the above-mentioned authors— 
we must evidently find in the fact, that we are always accustomed 
to apply the stimulations during the diastole or shortly afterwards, 
but with few exceptions only in the end of the pause and certainly not 
of the long pauses that oceur with the halved rhythm. And after- 
all there is a 2"¢ moment of the heart-period in which 1 can apply 
an extra-stimulation with as much success in order to restore the 
normal rhythm. Jf I apply namely in the latter part of the 
pause, or in the beginning of the auricle-systole after the pause, an 
extra-stimulation either to the apex ventriculi or to the base, the normal 
rhythm restores itself also from the halved one (vide Fig. 5 at 0). 
The extra-stimulation now causes an extra-systole, which happens to 
be rather large. Its great height may be explained by the fact that 
we register now at the same time a shortening of the ventricle- 
and the auricle-musculature. The fact that the ventricle is less full 
may perhaps likewise exercise some influence. This extra-systole 
occurs now at an earlier moment than the normal ventricle-systole 
of the halved rhythm would have appeared. With the systoles of 
the halved rhythm the second anricle-systole falls at the end of the 
systolic plane. With this extra-systole the next auricle-systole occurs 
at the end of the diastole, and can for this reason be succeeded by 
a ventricle-systole, which is small on account of the short pre- 
ceding interval, and introduces for this reason the normal rhythm 
as in Fig. 1. 
Here in Fig. 5 the normal rhythm is introduced by the normal 
physiological “Erregung” at the end of the diastole of a large extra- 
systole. The two experiments can be'executed equally easily. It is eon- 
sequently evident, that in two indicated places we can, during the 
period of the halved rhythm, by extra-stimulation of the ventricle- 
muscle convert this halved rhythm into the normal one. This restored 
normal rhythm passed after twelve systoles into bigeminy, which I 
converted again into the normal rhythm during the third group 
by an extra-stimulation, which was applied a little earlier in the 
diastole. After twelve systoles this normal rhythm changed again 
spontaneously into bigeminus-groups (as in Fig. 4). After about 
3 minutes | converted these bigeminus-groups into the. normal 
rhythm by an extra-stimulation, which was applied towards the end 
