CHAPTER V 

 THE HEART 



THE NATURE OF THE HEART-BEAT 



Inve.stigation into the nature of the heart-beat may be 

 said to have been inaugurated in 1852 wnth the experi- 

 ments of Stannius upon the frog's heart. Previous to this, 

 all that was known with certainty was that the beat was 

 independent both of connection with the central nervous 

 system, and of the presence of blood in the cavities. 

 Stannius found that when a hgature was tied at the junction 

 of the sinus and auricle (Stannius's First Ligature) the sinus 

 continued to beat while the auricle and ventricle stopped. 

 This he attributed to paralysis of Remak's ganghon 

 situated at the site of the Hgature. On applying a ligature 

 between the auricle and ventricle (Stannius's Second 

 Ligature) he found that while the auricle remained quiescent, 

 the ventricle resumed beating. This he considered to be 

 due to a stimulation of Bidder's ganglion situated at the 

 junction of these two chambers. Stannius's experiment, 

 therefore, seemed to confirm the view already held that the 

 cause of the beat lay in the activity of the nerve-cells 

 embedded in the heart- wall. 



In 1881, the accuracy of these experiments and the 

 interpretation put upon them by Stannius were called in 

 question by Gaskell. Gaskell drew attention to the fact 

 that the stoppage of auricle and ventricle following the 

 first ligature was only temporary, and was soon followed 

 by the development of rhythmic contraction of these 

 chambers slower than and independent of the contraction 

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