AN ANATOMICAL STUDY ON THE 



single weak and feeble beat to two or three pulsa- 

 tions of the auricles.^ 



With the auricles still pulsating after the heart 

 has stopped, it is noteworthy that a finger placed 

 on the ventricles perceives the separate pulsations 

 of the auricles for the same reason as the beat of the 

 ventricles in the arteries is felt, because, as was 

 said before, of the distention from the impact of 



' The first observation of heart-block. The great Haller (1708- 

 1777) later postulated a peristaltic muscular wave from the vena cava 

 to the aorta over the heart, but Moritz Schiff (i 823-1 896), by noting 

 again what Harvey had observed in the dying heart, showed this con- 

 cept untenable. The term "heart-block" was introduced by W. H. 

 Gaskell (1 847-1914), in his masterful analysis of the heart beat (Phil. 

 Tr., Lond., 173: 933, 1882) which soundly established the "myogenic" 

 theory of the movement. In this treatise "it is shown that the motor 

 influences from the nerve ganglia in the sinus venosus influence the 

 rhythm (rate and force) of the heart, but do not originate its move- 

 ments or beat, which are due to the automatic rhythmic contractile 

 power of the heart muscle itself and to the peristaltic contraction wave 

 which proceeds from sinus venosus to bulbus arteriosus and from 

 muscle fiber to muscle fiber" (Garrison). Much of this may be deduced 

 from Harvey's observations in this Chapter. Gaskell's studies were 

 extended by T. W. Engelmann (i 843-1909). They gave a new inter- 

 pretation to the classical experiments of H. Stannius (1808-1883) who 

 showed (Mtiller's Arch., 1852, 163) that a ligature around the sino- 

 auricular junction would stop the heart, while a second ligature around 

 the auricular-ventricular groove would be followed by slow ventricular 

 beats. W. His, Jr., in 1893, found a thin strip of muscle between the 

 auricles and ventricles, which according to Gaskell's ideas, serves 

 as the conducting medium for the contractile impulses between auricles 

 and ventricles. The clinical significance of heart-block or Stokes-Adams 

 disease was first emphasized by R. Adams (1791-1875) in the Dublin 

 Hospital Reports 4: 396, 1827, and by W. Stokes (i 804-1 878) in the 

 Dublin Quarterly Journal of Medical Science, 2: 73,1846. The clinical 

 study of these phenomena has been greatly facilitated by electrocardio- 

 graphic methods developed chiefly by W. Einthoven (K. Acad. Amster. 

 Proc. Sect. Sc, 6: 107, 1903). 



[40] 



