Formerl}' (lie sliiiiiilus was twice liaiisuülied d mini!,- one ventricle- 

 systole along this track, now only once; formerly on each ventricle- 

 systole two anricle-systoies occurred, now only one. ') 



That the hiatns, cansed by the falling ont of one auricle-systole 

 is indeed not the cause of the shortening of the a-w-interval is 

 proved by the further progress of the curves. Thus we see in the 

 lower row of curves of Fig. 3, which is rej)resented 5 minutes after 

 that of the former figure, the i:<-(;-iiiterval still constantly shortened. 

 The upper-row of curves of Fig. 3 was registered 10 min. before 

 that of Fig. 2. We must pay attention to the fact that, when noting 

 down the curves of Fig. 3, llie rotations of tiie drum were quicker, 

 and for the lower row again quicker than for the upper row ; 

 consequently tiie curves are drawn out more in width. 



I'^ig. 4. 

 Dmiiig the tiist 4 systoles halving of the ventricle-rhythm. 

 Thereupon the rhythm uf the auricle halves likewise. The 

 llrst aiiricle-systule that falls out ought to have stood on the 5''' 

 ventricle systole. This is the cause that there occurs no 

 hiatus. The (M'-interval after it is shortened. The curves show 

 the falling out of every 2ih1 auricle-systole as the tops of the 

 ventricle-curves become rounder. 



We see in Fig. 4 another example. Half an hour after the in- 

 jection of 8 drops of 1 7o acetas veratrini the ventricle-rhythm of 

 this frog's heart wa.s halved, half an hour later when a few times 

 variations of the ventricle-rhythm had taken place, the rhythm of 

 the auricle halves. The first auricle-systole falls out on the top of 

 the fifth ventricle-systole of the figure. The acute ventricle-top 

 becomes by the falling out of the auricle-systole, that stood on its 

 top, obtuse and rounded off (by looking at the heart I have also 

 observed that afterwards on each auricle- one ventricle-systole 

 occurred). Because the first auricle-systole, which falls out, ought 

 to have come on the top of the ventricle-curve no hiatus occurs now. 

 The shortening of the r/-<;-interval is also here obvious. By exact 

 measurement we see, that after the halving of the auricle-rhythm 



') The stage of the latent irritation of the auricle will certainly be shortened, 

 but we may safely admit, that this has no intluence on the a-yinterval, only the 

 si-«-interval is shortened by it. 



