407 



alternations between the normal ventricle-rhythm and the halved 

 one. 1 succeeded in photograpliing such a spontaneous alternation 

 under simultaneous registration of the action-currenls. 



This reproduction shows a great number of important details, 

 and atfords a formal confirmation, likewise for not-poisoned frogs' 

 hearts, of the theoretical explanations communicated by me in former 

 essays. In the figure we see suddenly appear the halved ventricle- 

 rhythm after 4 normal ventricle-systoles. Three of these are still 

 registered. 



I intend more explicitly to explain here the following details, which, 

 in my opinion, are of interest for my subject. 



1. As 1 indicated in my former investigations the a-v-interval 

 increases during the normal ventricle-rhythm till the halving of the 

 ventricle-rhythm sets in. Afterwards the duration of the a-v-interval 

 decreases. The suspension-curves of this figure show a much shorter 

 a-v-interval after the halving than before it. But the electrograms 

 indicate these differences much sharper. The P-R-in(erval increases 

 still during the last 4 systoles. The first curve of the halved ventricle- 

 rhythm shows a much shorter P-R-interval of the normal ventricle- 

 rhythm. The restoration of the ventricle-muscle in the halved rhythm 

 is even distinctly to be seen in these 3 first curves of the halved ventricle- 

 rhythm. The P-R-interval of the 2"<^ systole is shorter than that of 

 the first, and that of the 3"i still shorter than that of the 2'«^. 



We must attribute the shortening of the P-R-interval after the 

 halving to a shortening of the electric latent stage, as all sinus- 

 impulses reach the ventricle along the connection-systems (Bundle of 

 His), and consequently the time of conducting along these has not in 

 the least changed. It appeal's that this sliortening still proceeds 

 from the moment of the first ventricle-systole of the halved rhythm. 



2. The duration of the R-oscillation is after the halving shorter 

 than before it. This duration is now also again shorter during the 

 2"^^ systole than during the first, and at the S'^^- systole shorter than 

 at the 2"^. 



In the halved ventricle-rhythm the conductivity through the 

 ventricle is consequently better than in the normal twice as rapid 

 rhythm of the ventricle. From the first systole of the halved ventricle- 

 rhythm the conductivity still improves from systole to systole. 



The P-R-interval and the duration of the R-oscillation conse- 

 quently sustain alterations in exactly the same sense. We must attri- 

 bute both these alterations to the changed metabolic condition of 

 the ventricle-muscle (katabolic index). This metabolic condition deterio- 

 rates in the normal ventricle-rhythm. If now -the rhythm of the 



