38 



the a-i^-iiitei'val is not siulileiily reduced to the delinilive extent, bnt 

 becomes smaller from systole lo svstole; lliiis before lliis halving 

 the a-^'-interval amounls lo i'/, see., for the first systole after the 

 halving- of the auriele-rhythni i '/«. 'o'' '''C seeond J'/io t'" '"'' '''^ 

 fifth, sixth and seventh this amount is 1 see.; l'/.^ nun. later (vide 

 Fig. 5 lower row) this amount is likewise still 1 see. The upper- 

 row of curves of Fig. 5 has been represented 15 min. before the 

 lowei'. Here we see a variation of rhythm of the ventricle. 



Fig. 5. 



The lower row of curves lias been represented IV3 minutes 



after the curves of fig. 4. The a-r-interval is still shortened. The 



upper row has been represented 15 minutes before the lower. 



We see hereupon a variation of rhythm of the ventricle. 



When estimating the variations of the r/r-iuterxal we must con- 

 sequently always ask, which amount of it must be attributed to the 

 transmission of stimuli, and which amount is caused by the possibility 

 of exerting influence upon the ventricle-musculature. So the shortening 

 of the a-r-interval after the halving of the ventricle-rhythm must 

 be attributed to the improved possibility of exerting infhience npon 

 the ventricle-musculature. If the rhylhm of the auricle halves at the 

 same time as that of the ventricle, then both factors contribute to 

 the shortening of the a-w-interval. 



For the extra-sy.stole after irritation of the auricle both factors 

 contribute to lengthen the a-r-interval, for the then succeeding post- 

 compensatory systole to shorten the a-r-biterval. For the post-com- 

 pensatory systole after extra-irritation of the ventricle the a-r-interval 

 is again shortened liy the possibility of exerting influence more 

 rapidly upon the venti-icle-musculature. 



We shall however continue to speak of the power of transmis- 

 sion of the connecting-systems, and estimate this in accordance with 

 the a-r or P-/?-interval, bnt the above evidence must guide us when 

 drawing our conclusions. 



Along a (piite difiterent way I showed that the ventricle-systoles 

 have a latent stage for the irritation coming from the auricle, of a 



