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Mr. T. Lewis. 



bridges. As a sequel the attention of workers gradually became focussed to 

 discover (1) the precise point at which the contraction originates and (2) the 

 precise paths followed by the natural wave as it travels over the heart. 



I do not propose to follow in detail the growth of knowledge from the 

 time of Gaskeli's experiments ; I shall be content to enumerate the chief 

 steps as they were taken ; neither shall I follow those steps in their exact 

 chronological order. Gaskell worked upon the relatively simple hearts of 

 the frog and the tortoise ; my own object as a clinician has been an 

 understanding of the motion of the mammalian organ ; to this, therefore, 

 I shall now in the main confine myself. 



For several reasons, investigation of the mammalian heart is more 

 difficult than that of the cold-blooded heart. The mammalian organ is 

 more viable, it is more complex, its movements are far more rapid. The 

 blood stream through the mammalian heart has to be maintained, the 

 heart insists upon respectful treatment, otherwise the natural beat is not 

 maintained. I lay particular emphasis upon the fact that those methods of 

 investigating the mammalian heart which subject the organ to the least 

 manipulation and damage are the methods which are most successful in 

 elucidating the nature of its beating. The rapidity with which the 

 contraction wave passes over the tissues of the mammalian heart necessitates 

 the use of delicate apparatus in its study. Our methods of registering the 

 movement in different heart chambers have improved very rapidly of recent 

 years ; systems of recording levers have become ever lighter and quicker in 

 their movement, but mechanical contrivances, much as they have been 

 employed for the purpose, have so far proved inadequate. For accurate 

 observation, electrical methods have almost wholly replaced them. In 1878 

 the first records of the heart beat were taken by Burdon-Sanderson and 

 Page (21), using the capillary electrometer ; their work upon the tortoise 

 heart may be regarded as the real starting point of modern electrocardiography. 

 Five years later Waller (24) showed that the beat of the heart may be 

 recorded in mammals (including the human subject), without exposing 

 the organ, without damaging the animal in any way. In 1892 the 

 mammalian ' heart was the subject of special study by Bayliss and 

 Starling (1). These early galvanometric studies, while throwing little 

 actual light upon the course of the contraction wave, are, nevertheless, to 

 be regarded as essential steps ; they opened up a new pathway, which later 

 workers have pursued ; in this sense the workers were pioneers. It was in 

 the present century that Einthoven (4), in Holland, perfected an instrument 

 which, on account of the facility of its working and the precision of its 

 movements, has enabled us to unveil much which was formerly mysterious. 



