302 



PH YSIOLO< ; Y 



CHAP. 



This fact is shown (owing to the special character of the apparatus) 

 in the curve of Fig. 129 as an ascending staircase, produced by the 

 progressive increase not of systole, but of diastole, in proportion 

 as the tone of the myocardium diminishes. For when a second 

 ligature is applied to the auricles, the heart being already connected 

 with the recording apparatus, the tracing assumes a tetanic form, 

 and the beats, as they become more excursive, rise above a regularly 

 descending line, which is the exact expression of the progressive 



Fie. 132. it tan i /in-ill jii' I'ui/fim commencing at c. after provisory ligature of auricles; converted 

 at b into slightly ascending staircase, the beats becoming less frequent, after removal of 

 ligature, (l.nciaui.) 



decrease in tonicity (Fig. 130). If, after applying the second 

 ligature to the auricle, the valve which separates the heart from 

 the vessel of serum is opened, the beats which accompany the 

 attack assume the form of an ascending staircase, as in Fig. 129, 

 which bears out our interpretation (Fig. 131). Practically the 

 same result is obtained if the ligature is applied soon after the 

 paroxysm has commenced (Fig. 132). 



FIG. 133. Pei-indk- rliythiii shown by frog's heart tied at the auricles, 2 mm. above the 

 auriculo-ventricular groove, tilled with rabbit's serum and attached to tonographic apparatus 

 of Fig. 121. (Luciani.) The figure shows four periods of regular increase, both in number of 

 beats in groups and in duration of pause. The divisions along the abscissa represent 

 intervals of 1 second. 



The phenomenon of " paroxysm," which shows that the 

 ligature applied at different heights of the auricles (in conjunction 

 with the action of serum and of a certain degree of pressure) 

 invariably acts not merely by separating, but also by contusing 

 and irritating the walls of the heart, seems to us the most direct 

 refutation of the doctrine of the twofold nature of the cardiac 

 ganglia, 



When the paroxysm is < > ver, a new phenomenon appears which 

 we have termed periodic rhythm, in which the cardiac pulsations 



