110 THE CIRCULATION. 



summit of Mont Blanc, his pulse was about double the ordi- 

 nary standard all the time he was there. After six hours' 

 perfect rest and sleep at the top, it was 120, on descending to 

 the corridor it fell to 108, at the Grands Mulcts it was 88, at 

 Chamounix 56 ; normally, his pulse is 60. 



In health, there is observed a nearly uniform relation be- 

 tween the frequency of the pulse and of the respirations ; the 

 proportion being, on an average, one of the latter to three or 

 four of the former. The same relation is generally main- 

 tained in the cases in which the pulse is naturally accelerated, 

 as after food or exercise ; but in disease this relation usually 

 ceases to exist. In many affections accompanied with in- 

 creased frequency of the pulse, the respiration is, indeed, also 

 accelerated, yet the degree of its acceleration bears no definite 

 proportion to the increased number of the heart's actions, and 

 in many other cases, the pulse becomes more frequent without 

 any accompanying increase in the number of respirations ; or, 

 the respiration alone may be accelerated, the number of pul- 

 sations remaining stationary, or even falling below the ordi- 

 nary standard. (On the whole of this subject, the article 

 Pulse, by Dr. Guy, in the Cyclopaedia of Anatomy and Physi- 

 ology, may be advantageously consulted.) 



The force with which the left ventricle of the heart contracts 

 is about double that exerted by the contraction of the right : 

 being equal (according to Valentin) to about -^th of the 

 weight of the whole body, that of the right being equal only 

 to youth of the same. This difference in the amount of force 

 exerted by the contraction of the two ventricles, results from 

 the walls of the left ventricle being about twice as thick as 

 those of the right. And the difference is adapted to the 

 greater degree of resistance which the left ventricle has to 

 overcome, compared with that to be overcome by the right ; 

 the former having to propel blood through every part of the 

 body, the latter only through the lungs. 



The force exercised by the auricles in their contraction has 

 not been determined. Neither is it known with what amount 

 of force either the auricles or the ventricles dilate ; but there is 

 no evidence for the opinion, that in their dilatation they can 

 materially assist the circulation by any such action as that of 

 a sucking-pump, or a caoutchouc bag, in drawing blood into 

 their cavities. That the force which the ventricles exercise in 

 dilatation is very slight, has been proved by Oesterreicher. 

 He removed the heart of a frog from the body, and laid upon 

 it a substance sufficiently heavy to press it flat, and yet so 

 small as not to conceal the heart from view ; he then observed 

 that during the contraction of the heart, the weight was raised ; 



