378 Dr. C. H. Jones on the Effects of Exercise [June 19, 



means the fact ; it is well known that a person in good condition will do 

 a given piece of work with far less acceleration of pulse than one who is 

 untrained. Thus a Londoner, in ascending a steep Surrey hill heavily- 

 weighted, had his pulse raised from 78 (while sitting still) to 120; but a 

 countryman, of rather stronger build, performed the same work with 

 much less acceleration. His pulse was 90 after he had walked to the 

 bottom of the hill, 96 at the top. An anoemic patient of miue had 

 her pulse increased from 78 to 160 by a slight exertion, which, when 

 she was stronger and had more blood, only raised it to 103. Graves 

 observed that the degree of acceleration of the pulse produced by sitting 

 up in bed is a good indication of the extent to which a patient is ex- 

 hausted. These facts seem to prove, per exclusionem, how much the 

 state of the nerve-force has to do with the pulse-rate. Direct experi- 

 ment (the section of the vagi) makes this still more certain ; moreover, 

 as acceleration of the pulse is met with very commonly in conditions of 

 febrile debility, and as a cause of exhaustion was present in all my cases, 

 it does not seem an unreasonable hypothesis, from all these premises, to 

 regard weakening of the regulating action of the vagi on the cardiac 

 nerve-apparatus as the cause of the increased pulse-rate, the vagi nerves 

 or their centres being weakened by the withdrawal of nerve-force to the 

 motor centres of the limbs. 



But though I can hardly doubt that this view is in the main correct, 

 harmonizing also as it does with that taken as to the cause of the in- 

 creased temperature, yet it seems to be opposed by the results obtained 

 with the manometer after division of the vagi. Dr. Sanderson finds that 

 in such experiments the contractions of the heart are sufficiently vigorous 

 to maintain an arterial pressure several inches higher than the normal. 

 But if I may trust my finger and the sphygmometer, the force of the 

 cardiac contractions and the resulting arterial pressure are generally de- 

 cidedly lowered by active exertion ; in fact we know that excessive 

 exertion may produce syncope. I cannot attempt to reconcile this dis- 

 crepancy. Acceleration of the pulse-rate per se seems to have no influ- 

 ence in increasing the intravascular pressure. This conclusion seems to 

 follow from an examination of the sphygmometer records and of the 

 tracings, which, in the majority of instances, show weakening of the 

 cardiac force. 



In judging of the Tracings, it may be assumed that in the state of 

 quietude there is a certain amount of nervo-muscular force put forth by 

 the heart arid arteries with their nerve-centres, such as can be con- 

 tinuously and without effort produced, and that the amount exhibited in 

 the conducting is duly proportioned to that in the impelling organs. 

 The plan of the circulation evidently requires that the heart's force 

 should greatly exceed that of the arteries, that the latter should yield 

 and dilate under the pressure of the blood-current on their inner surface ; 

 and this seems very constantly to take place. Moderate exercise, which 



