NEWER ASPECTS AND METHODS IN THE STUDY OF 

 THE MECHANISM OF THE HEART-BEAT. 



By ALFRED E. COHN, A.B., M.D. 

 (Read April 23, 1914.) 



The interest now very widespread, in the physiology of the 

 heart-beat developed from certain observations which Carlo Mat- 

 teucci made some seventy-two years ago, and which he communi- 

 cated in 1842 to the Academy at Paris. He established the fact that 

 the muscle of a nerve-muscle preparation contracted if its nerve 

 were laid across a second muscle which had been made to contract. 

 He believed that the stimulus which the nerve received, and which 

 it conveyed to its attached muscle was electrical in nature. Thirteen 

 years later, in 1855, Kolliker and H. Miiller widened the scope of 

 Matteucci's observations by demonstrating in the same way that, if 

 the nerve of a similar nerve-muscle preparation were laid across a 

 heart, the muscle of the preparation likewise contracted, because, as 

 in Matteucci's experiment, a current, called a current of action, was 

 discharged from the contracting heart and was conveyed to the 

 muscle. 



These discoveries continue to be the primary subjects of experi- 

 ment in contemporary studies in the mechanism of the heart-beat. The 

 first experiments dealing with action currents were made by Mar- 

 chand, Engelmann, and by Burdon-Sanderson and Page, who used 

 a Bernstein rheotome in their investigations, but later the use of the 

 capillary electrometer of Lippmann was introduced, especially by 

 Marey, Waller, by Bayliss and Starling, Gotch and others. Marey 

 in 1876 was the first to obtain permanent records of the action cur- 

 rents of the heart by photographing the motions of the meniscus of 

 the mercury column of the electrometer on a moving sensitive 

 surface. This record was a continuous curve in which could be 

 distinguished various waves, one of which has been identified as 

 synchronous with the contraction of the auricles, the upper chambers 



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