WALTER IIOLBROOK GASKELL LANGLEY. 525 



by the nerve cells of the sinus venosus. There were very varied views 

 as to the method of working of the nervous mechanism, especially as 

 to the parts played by the nerve cells of the septum of the auricle, 

 and the nerve cells of the base of the ventricle. As it became more 

 widely recognized that parts of the heart which had no discernible 

 nerve cells could contract rhythmically, it was felt that the nervous 

 theory did not account for the whole of the phenomena. Moreover, 

 some of the pharmacological results could not be satisfactorily ex- 

 plained on the theory as then put forward. But no one had any 

 more satisfactory explanation to offer. 



The question of the action of the nerve cells in the heart was part 

 of the general question of the functions of the peripheral ganglia. 

 In 1869, Engelmann argued that the peristaltic contraction of the 

 ureters did not depend on nerve cells and that the contraction was 

 conducted from one muscle cell to the next without the intervention 

 of nerve fibers. In 1875 he advocated a similar view as regards the 

 passage of contraction from one part of the ventricle of the frog's 

 heart to the rest, and he thought this was probably also the case in 

 the auricle. But in one important point he kept to the old theory and 

 considered that the passage of contraction from auricle to ventricle 

 was brought about by nerve cells and nerve fibers. Gaskell (1881) at 

 first adopted the current theory with some modifications in detail, but 

 in 1883 he abandoned it, and a'rgued that the contraction of the heart 

 was of muscular origin; it started in the sinus and spread as a peris- 

 taltic wave to the other chambers, the delay in the passage of the 

 contraction wave from one chamber of the heart to the next being due 

 to a slow conduction in the modified muscular tissue which he found 

 at the junction of the sinus venosus with the auricle, and at the 

 junction of the auricle with the ventricle. In the course of his work 

 Gaskell made a large number of original observations on the be- 

 havior of the several parts of the heart and of the cardiac muscle. 

 The term " block " Gaskell adopted from Romanes's account of the 

 passage of contraction waves in Medusa3; the phenomena had been 

 partly worked out in the frog's ventricle by Engelmann, but they 

 were much more completely elucidated by Gaskell's work on the heart 

 of the frog and the tortoise. It was known that the contraction of 

 the ventricle might only occur at every second, third, or fourth beat 

 of the auricle. Gaskell obtained this effect experimentally by vary- 

 ing the degree of block between the two chambers. After the lapse 

 of years the invention of the string galvanometer brought the obser- 

 vation of heart block in man into the region of clinical medicine. 



The different effects produced on the heart of the frog by stimu- 

 lating the vagus nerve were investigated simultaneously by Gaskell 

 and by Heidenhain. Gaskell observed that stimulation of the vagus 



