the First Sound of the Heart is produced. 



335 



resembles most nearly that of carriages at a very great distance 

 passing rapidly over a rough pavement." * It is very difficult to 

 conceive the slight, soft, rolling sound produced by muscle in action 

 being convertible into the loud, booming first sound of the heart. 

 Yet the theory is accepted. If muscle during contraction could pro- 

 duce so marked a sound, we should expect to find that the powerful 

 muscles of the neck attached to the base of the skull and those 

 attached to the jaw (being through the bones of the skull in direct 

 relation with the hearing apparatus) would give us some striking 

 evidence of the production of muscular sounds when they are thrown 

 into strong action. It is reasonable, too, to believe that such muscu- 

 lar sounds must occur and be heard, if they exist, during the move- 

 ments of the athlete or the boxer as well as during the performances 

 of the danseuse. But there is nothing of the kind. I have failed to 

 hear such sounds when listening to the powerful contraction of the 

 biceps, or on listening to the contraction of the shoulder muscles of 

 a strong cart-horse struggling with a heavy load in ascending a hill. 

 I could hear no other sound save the soft, rolling sound described by 

 Dr. Wollaston. Still many observers have argued that the contrac- 

 tion of the walls of the heart differs from the action of the skeletal 

 muscles, and that it is this peculiar form of contraction which causes 

 the first sound. They have adduced so many observations in favour 

 of this doctrine that it will be necessary to examine them. But 

 before doing so, for the sake of making my argument more clear, I 

 desire to point out that there is another event which occurs simul- 

 taneously with the systole of the ventricle. This is the propulsion of 

 the blood from the ventricles and its impact against the column of 

 blood resting on the semi-lunar valves. 



With a view to showing how large a share the sound of muscular 

 contraction has in producing the first sound, observers have cut off 

 altogether the supply of blood from the cavities, and on listening 

 during the contraction of the heart have heard a systolic sound. 

 Such were the old experiments of Ludwig and Dogiel, represented 

 as confirmed by Krehlf and by Kasem-Beck.J 



The conclusions which have been drawn from these experiments 

 are disproved by those conducted by my friend Professor Halford, 

 and described in his essay on "The Action and Sounds of the 

 Heart,'* published by Churchill (1860). He writes: "Large dogs 



* It is interesting to note that Dr. Wollaston, in examining the sound produced 

 by the muscles of his leg, made use of a wooden rod to convey the sound to hi* 

 ear. He may be thus said, in a measure, to have anticipated the principle of 

 mediate auscultation discovered by Laennec in 1816. The muscular sound which 

 we now recognise is that accurately described by Wollaston. 



t ' Du Bois-Reymond's Archir,' 1889, p. 253. 



X 1 Pfluger's Archiv,' vol. 47, p. 53. 



