SOUNDS OF THE IIEALT. O 



fact that they possess a power of independent pulsation was 

 known to Haller,* and was brought prominently forward by 

 Senac,t who regards the vena cava as the starting point of the 

 whole circulation. He says : " The vena cava is therefore the 

 first motor cause which dilates the cavities of the heart ; it fills 

 the auricles, and extends their walls in every direction." 



These observations appear to have been almost forgotten 

 until they were again made independently a few years ago,t 

 and in one of the latest and most accurate physiological treatises 

 which now exist, the description of the cardiac cycle is nearly 

 the same as that given by Senac. "A complete beat of the 

 whole heart, or cardiac cycle, may be observed to take place as 

 follows : — 



" The great veins, inferior and superior ven?e cavse and pul- 

 monary veins are seen, wdiile full of blood, to contract in the 

 neighbourhood of the heart ; the contraction runs in a peri- 

 staltic wave towards the auricles, increasing in intensity as it 

 goes."§ 



The pulsation of these veins, however, cannot be a constant 

 phenomenon, or it would have been noticed by such a keen 

 observer as Harvey. 



The sounds of the heart were discovered by Harvey, or at 

 least were known to him, for he speaks of the sound caused in 

 the oesophagus of the horse by drinking, and says : " In the 

 same way it is with each motion of the heart, when there is a 

 delivery of blood from the veins of the arteries that a pulse 

 takes place, and can be heard within the chest." }| 



This observation remained, as far as we know, without any 

 further development until the time of Laennec, who introduced 

 the practice of auscultation ; but it was a Fellow of this College, 

 Dr. Wollaston,^ w^ho first discovered that muscles during con- 

 traction give out a sound. Although many observations were 

 made regarding cardiac murmurs by Corrigan, Bouillaud and 



* Haller, Ulementa PJiysiologice, 1757, tome 1, pp. 410 and 399. 



+ Senac, De la Structure du Coeur, livre iv, ch. iii, p. 24. 



X Froc. Hoy. Soc, 1876, No. 172. 



§ M. Foster, Text-book of Physiology, 6th edition, pai't i, ch. iv, p. 231. 



II The Works of William Harvey, Sydenham Society's edition, p. 32. 



% Wollaston, £hil. Trans., 1810, p. 2. 



