410 



The heart of a rana temporaria was suspended and soon showed 

 group-formation, because constantly J systole of the ventricle fell 

 away. The groups grow gradually smaller, till groups of 2 and 3 

 systoles (fig. 4) form the last transition to the halved ventricle- 

 rhythm, (fig. 5). We see during the groups the duration of the a — v 

 interval increasing splendidly ; again and again the ventricle-systole 

 sets in later in the auricle-diastole, till one ventricle-systole falls 

 away. After this the interval is shortened again, to bè protracted 

 again in the same way during the following group. The ventricle- 

 systole of each first curve of the group commences in the figures 

 2, 3 and 4 close to the top of the auricle-curve. The ventricle 

 systole of each last curve begins at about the middle of the diastolic 

 line of the auricle-curves. This is the case with the large groups, 

 but also with the little ones (bigeminus groups). Consequently in the 

 beginning more systoles of the ventricle are required than later to 

 protract the a — 2;-interval as much. The deterioration of the meta- 

 bolic condition of the ventricle-muscle is aniiounced here by the 

 formation of smaller groups. It is likewise clear, that during the 

 groups the metabolic condition of the ventricle-muscle deteriorates, 

 and improves again after a protracted pause. In my opinion we 

 must here also attribute the protraction of the a — v-interval again 

 to a protraction of the latent stage of the ventricle-muscle. 



It is the active contracting terminal organ, the ventricle-muscle, 

 the refractory stage of which increases during the groups and so 

 does at the same time likewise the latent stage. The increase of 

 the refractory-stage is here likewise caused by the increase of the 

 duration of the residue-refractory-stage by accumulation. During the 

 protracted pause after a group the decrease of the residue-refractory- 

 stage surpasses the inci-ease of the periodical refractory-stage. In 

 this way the constantly decreasing groups come into existence, which 

 ends in the halved ventricle-rhythm. 



The conductivity through the ventricle was examined by me 

 still in another way. In a former communication it was already 

 stated, that the T-oscillation had altered in a negative sense 

 after extra-stimulation of the ventricle-basis or of the auricle. A 

 positive T of the normal ventricle-systole decreased during the extra- 

 systole which was excited in this way, a negative T increased. In 

 some cases a positive T became negative. The T oscillation had 

 changed in a positive sense after extra-stimulation of the ventricle- 

 point. A negative T decreased, a positive one increased ^;. 



1) Zeilschrift fur Biologie. Bd 65, Seite 428. 



