240 



traiisiiiissioii-\el()('il_v ol' tlie uliimiliis is not foiisiderably disturbed; 

 tbr if till" stiiniiliis transmits itself slower, the point will interfere 

 later with the basis, and thereby the height will be able to increase 

 already). The influence of the refrigeration of the sinus venosus on 

 the electrograms and the mechanical curves is here entirely a con- 

 sequence of variation of frequency. The duration of tiie /^-oscillation 

 becomes shorter on account of the improved transmission of excitation 

 after the longer pauses, but the duration and height of the 7-oscil- 

 lation likewise increase consideraliiy. Tiie meciianogram likewise 

 increases in height and duration. 



A well-defined example of transition of alternation into the normal 

 rhythm represents Fig. 7. The height of the mechanograms of the 

 normal rhythm stands between the heights of the alternation-systoles. 

 In the electrograms the .same proportion is found back for the 

 heights of tiie ^'-oscillations, and likewise for llie de|)ilis of the 

 incisions, caused in the electrograms by the interference of the apex 

 negativity with the negativity of the b.asis. 



In Fig. 8 (page 238i we see an alleniatioii thai 1 luul canscii 

 bv calefaction of the sinus venosus, change again inio the normal 

 one Im rel'ri,i;cranon of the sinus (the niomeiil of refrigeration is 

 iiulicated by llie signal) (_>ccasionally llie alternation was (inly to 

 lij asccit.iiiuMi by a difference in height of the 7-oscillatioiis. Tli^i 

 highest 7"s lielonged then lo the lowest systoles. This can only be 

 explained by an inferior interference of the ape.x-part with the l)asis. 



Not always, however, does (he point parlicijiale less during the 

 lilllc s\ stoles; in some cases the elertograin can only be understood, 

 if allerni\tiniily we admit a diminished parlici|)ation of the basis, or 

 also, if alternalingly now the basis, now the point pulsated. 



So Fig. 9 (|)age 239) allows us to doubt, whether here the little 

 systoles are occasioned by exclusively basis-systoles. 



I have another representation in which during the little systoles 

 for the greater part the point pulsates, and during the large systoles 

 the basis does so. These however are exceptions. As a rule I observed 

 that during the little systoles the point does not participate. In 

 nearly all representations the large systole begins later after the 

 expiration of the preceding systole than the little one. This can 

 distinctly be observed from the electrograms. Con.seqnently besides the 

 systoles the pauses alternate also, whilst an alternation in the duration 

 of the heartperiods does not occur. After it has appeared from the 

 electrograms, that the heart-alternation of the extirpated frog's heart 

 is caused by i)artial asystole of part of the ventricle-musculature 

 (mostly of the [)oint). Fig. 2 suddenly becomes also more intelligible. 



